"Chemistry" Grade- 9 (New Course)

Unit -14

                    Atomic Structure and Chemical Bond

Chemistry : The branch of Science consisting the study of matter is called chemistry .
Matter :Any substance which occupies space and have mass is called mater .For example :air water, Hydrogen, stone etc.

Element:Element: The pure substance which can not be converted or broken down into two or more simpler substance by any physical or chemical process is called element .There are about 118 elements in the nature .Out up these 92 elements are found in nature or formed naturally are called natural elements .Remaining 26 elements are man made, are called artificial elements .
On the basis of chemical and physical properties elements are divided into 3 types :They are :i) Metal i.e. Iron ,gold , silver etc.
ii.) Non metal : Hydrogen ,oxygen ,carbon ,etc.
iii.)Metalloid: Arsenic, antimony etc.
They are generally found in 3 states i.e. Solid e.g. :Gold ,silver ,Liquid e.g.: Mercury ,bromine ,and Gas e.g.: Hydrogen ,Oxygen ,etc  

Atom : The smallest particles element is called atom .For example: Atoms of  H. O, N, Na, Al, C, etc.
Properties of atoms: i.) They takes part in chemical reaction  without division.
ii.)They are electrically neutral .
iii.)They can neither created  nor destroyed .
iv)  They can not be further divided .
iv)It is the smallest unit of an element .
v)Except hydrogen all atoms are made up of electron, proton, and neutron.
vi)Except atoms of inert gases ,all other atoms do not exist independently .

Molecules: A smallest particles of an element or compound which can exist freely in nature is called molecule .The molecule of an element is made up one or more atoms of the same type .For example : molecule of oxygen (O₂), molecules of Hydrogen(H₂) .But molecule of compound made up dissimilar atom .For example :molecule of water which consist of two atoms of hydrogen and one atoms of oxygen .They do not take part in chemical reaction .
Properties of molecules :
i)Molecules is smallest particles of an element or compound which can exist freely in nature .
ii) They are chemically decomposible .
iii)In molecule atoms are bonded together by chemical bond .

Atomic Structure:
Sub –atomic particle :According to Lord Earnest Rutherford an is made of three smallest particles i.e. Proton ,neutron, and electron are called subatomic particles .
Proton: The positively  charged subatomic particles is called proton .They are located in the Nucleus of atom .The mass of proton is equal to the mass of hydrogen i.e. 1 a.m.u. (atomic mass of unit ). It is denoted by P⁺ .
Neutron :The charge less  or Neutral subatomic particles of is called Neutron .They are located in the nucleus of an atom .The mass of neutron is equal to proton i.e. 1 a.m.u. It is denoted by n⁰ .
Electron : The negatively charged subatomic particle is called neutron .They are revolving around nucleus in an elliptical orbit .The mass of electron is about 1/1837 times the mass of hydrogen  or 1/1837 a.m.u. .It is denoted by e^- .
Nucleus   and Nucleons: The small   positively charged central part of an atom is called Nucleus .All protons and neutrons are present in the nucleus .
The protons and Neutrons present in the nucleus of an atoms are collectively known as nucleus .

Atomic number :The number of protons or electrons in an electrically neutral atom of an element is called atomic number .For example :H =1, He =2 ,Li =3 etc
Atomic number = N. of protons or N. of electrons
Atomic weight :The sum of number of protons and number of electrons in an atoms of element is called atomic mass . For example :atomic mass of He =2+2 =4  ,carbon =6+6=12 ,Nitrogen =7+7=14

Atomic number and atomic weight :

Atomic N. or Proton or electron	Name of element	Symbol	N. of Neutrons	Atomic mass or weight
1	Hydrogen	H	0	1
2	Helium	He	2	4
3	Lithium	Li	4	7
4	Berelium	Be	5	9
5	Boron	B	6	11
6	Carbon	C	6	12
7	Nitrogen	N	7	14
8	Oxygen	O	8	16
9	Fluorine	F	10	19
10	Neon	Ne	10	20
11	Sodium	Na	12	23
12	Magnesium	Mg	12	24
13	Almunium	Al	14	27
14	Silicon	Si	14	28
15	Phosphorus	P	16	31
16	Sulphur	S	16	32
17	Chlorine	Cl	18	35
18	Argon	Ar	22	40
19	Potassium	K	20	39
20	Calcium	Ca	20	40

Ion :The electrically charge atom is called ion .They have eight electrons to their valence shell .In ions number of electrons and protons are not equal .They are two types :
i)Cat ion  or positive ion :When an atoms losses electrons, it become positively charged and carries positive charge .Such positive charge atom is called cat ion .For example :  Ca⁺⁺  ,Mg⁺⁺,Na⁺, K⁺ etc
ii)Anion or Negative ion :When an atom gains electrons ,it become negatively charged and carries negative charge .Such negative charge atom is called an ion .For example :Cl^-, O^{- -}  ,Br ^– etc

Valency :The combine capacity of element or radical to another element or radial to form compound is called  valency .Or 
the capacity of element to sharing or losing of valence electrons to their valence shell is called valency . It is reperesented by the numbers i.e. 1,2,3,4,5,6, For example valency of Oxygen is 2 ,hydrogen is 1 .
Valence shell :The outer most shell of an atom is called valence shell .
Valence electrons :The number of electrons present in valence shell is valence electrons .Valence shell of valence electrons help to determine valency of element ,reactivity, Group of element,Metal,Non metal,Metalloid, etc . For example :valence electrons of oxygen is 6 so gaining capacity 2  electrons and valency is 2 , valence electrons of Mg is 2 ,so losing capacity is 2 and valency is 2 .
Penultimate shell :The second outer most shell or the inner shell next to valence shell is called penultimate shell .
Duplet and Duplet rule:  The state which is characterized due to presence of two electrons in  K shell is called duplet .
The tendency of an atom to hold 2 electrons in their first outer most shell is called duplet rule.For example :Hydrogen gain duplet by gaining 1 electron, Lithium obtain duplet by losing 1 electron, beryllium  obtain duplet by losing 2 electrons.
Octet and Octet rule : The state in which 8 electrons are arranged in the valence shell of an atom is called octet.
The tendency of an atom to hold 8 electrons ti their outer most shell is called octet rule .For example : Sodium obtain octet by lossing  1electron ,chlorine obtain octet by gaining 1 electrons.
1.)What do you mean that the valency of Al is 3 ?
Ans. It means that the combing capacity of Al is 3 i.e.It can donate electrons to other during compound  formation .

 Radical :A radical is an atom or group of atoms different element having positive or negative charge and act as single unit during chemical reaction is called radical .They are two types :
i)Electropositive radical or Basic radical :The radical which have the capacity of losing electrons and carry positive charge are called electropositive radical .For example Mg⁺⁺ ,(NH₄)
Radical                 Valency of elements                      Valency of radicals
Ammonium  (NH₄)   = + 5-4                          =      +1
 ii)Electronegative radical or acidic radical :The radical which have the capacity of gaining electrons and carry negative charge are called electronegative radical .For example :O^{-- --}  (SO₄)
Radical              Valency of elements                      Valency of radicals
Carbonate (CO₃)  = +4-6                                = -2
Bicarbonate (HCO₃)  = +1+4 -6                   = -1
Sulphate (SO₄)     = +6-8                                =2
Bisulphate (HSO₄)  =+1+6 -8                       =  -1
Nitrate (NO₃)  = +5-6                                                      = -1
Hydroxide (OH) = -2+1                                                  = -1

Valency chart :

S.N.	Name of Elements	Symbol		Valency
		Electro Positive	Electro Negative
1	Hydrogen  or hydride	H		1
2	Potassium	K		1
3	Sodium	Na		1
4	Silver	Ag		1
5	Gold-I(Aurous)	Au		1
6	Copper –I (Coprous)	Cu		1
7	Mercury –I(Mercurous)	Hg		1
8	Ammonium	(NH4)		1
9	Bicarbonate		(HCO3)	1
10	Bisulphate		(HSO4)	1
11	Hydroxide		(OH)	1
12	Bisulphite		(HSO3)	1
13	Nitrite		(NO2)	1
14	Nitrate		(NO3)	1
15	Chlorate		(ClO3)	1
16	Chlorite		(ClO2)	1
17	Chlorine or chloride		Cl	1
18	Bromine or bromide		Br	1
19	Fluorine  or fluoride		F	1
20	Iodine or iodide		I	1
21	Cyanide		CN	1
22	Bisulphite		(HSO3)	1
23	Barium	Ba		2
24	Calcium	Ca		2
25	Magnesium	Mg		2
26	Nickel	Ni		2
27	Zinc	Zn		2
28	Coppper –II(Cupric)	Cu		2
29	Iron –II(Ferrous)	Fe		2
30	Mercury –II(Mercuric)	Hg		2
31	Lead –II (Plumbous)	Pb		2
32	Magnanese	Mn		2
33	Tin-II(Stannous)	Sn		2
34	Iron –II(Ferrous)	Fe		2
35	Oxygen or oxide		O	2
36	Sulpher or Sulphide		S	2
37	Peroxide		H2O2	2
38	Carbonate		(CO3)	2
39	Sulphate		(SO4)	2
40	Sulphite		(SO3)	2
41	Chromate		(CrO3)	2
42	Dichromate		(Cr2O7)	2
43	Silicate		(SiO3)	2
44	Stanate		(SnO3)	2
45	Aluminium	Al		3
46	Gold –III (Auric)	Au		3
47	Iron-III (Ferric)	Fe		3
48	Chromium	Cr		3
49	Nitrogen or Nitride		N	3
50	Phosphrous  or phosphide		P	3
51	Phosphate		(PO4)	3
52	Lead –IV (Plumbic)	Pb		4
53	Tin-IV(Stanic)	Sn		4
54	Sulpher or sulphide	S		4
55	Silicon	Si		4
56	Carbon or carbide	C		4
57	Nitrogen or nitride	N		5
58	Phosphrous	P		5
59	Sulpher	S		6

Compound :The substance which is formed by the comb60ination of two or more elements by any chemical reaction in definite proportion by weight is called compound .
Properties of compound :
i)Compounds are formed by the combination of two or more elements in definite proportion by weight .
ii)They are formed by chemical reaction .
iii)Properties of compound are different from the properties of their constituents due to chemical reaction and chemical change .
iv)Compound are chemically pure substance .
v)Element of compound can be separated by chemical method.
Types of compound : They are two types :
1.)Electrovalent compound :-The compound  which is formed by transfer of  valence electrons between two atoms is called electrovalent compounds or ionic compounds .These compounds contains electrovalent bonds .They are formed generally from the combination of Metal and non metal .These compound can be electrolyzed .For example: Sodium chloride(NaCl ), Potassium chloride (MgO ) ,Magnesium oxide (CaCl₂) etc.
Properties :
i)Electrovalent or ionic compounds have high melting point .
ii)They are soluble in water .
iii)They do not have fixed geometrical shape .
iv)In fused or solution state  they conduct electricity .

1)NaCl
i)Na      –e^-  →        Na⁺  ion
Sodium
atom
ii)Cl      +e^-    →       Cl^-   ion
Chlorine
atom
iii)            Na⁺   +   Cl^-            →        Na⁺Cl^-    (NaCl)
       Sodium   Chlorine            (Sodium chloride
             ion            ion

2)MgO
i)Mg     -   2e^-   →    Mg⁺⁺ ion
Magnesium
atom
ii)O      +    2e^-   →   O^{- -}    ion
Oxygen
atom
iii)Mg⁺⁺          +    O^{- -}       →           Mg⁺⁺O^—(MgO)
Magnesium       Oxygen           Magnesium oxide
ion                      ion

3)CaCl₂
i)Ca       - 2e^-   →            Ca⁺⁺   ion
Calcium
Atom
ii)2Cl    +2e^-       →         2Cl^-  ion
Chlorine
Atom
 
iii)Ca⁺⁺     +   2Cl^-   →              Ca⁺⁺2Cl^- (CaCl₂)
Calcium         Chlorine       Calcium Chloride
Ion                   ion

2.)Covalent compound : The compound which is formed by sharing of valence cell of electrons between two elements is called covalent compound .These compound contains covalent bond .They are formed generally by the combination between non metals .These compound can not be electrolyzed. For example : Hydrogen Chloride (HCl),Methane (CH₄ ), water (H₂O) ,Ammonia( NH₄) etc.
Properties:-
i)Covalent compound have less melting and boiling point as compared  to electrovalent compound .
ii)They are insoluble in water but soluble in organic compound .
iv) They have fixed geometrical shape .
v)They do not conduct electricity .

1)HCl

H      +          Cl        →               H–Cl  (HCl)
Hydrogen      Chlorine        (Hydrogen chloride)
Atom             Atom

ii)H₂O 
2H       +     O          →           H–  O  – O   (H₂O)
Hydrogen     Oxygen                                    Water
Atom               Ato

                                                                                     

 

  3)Methane                                     H
      C    +    4H         →            H –  C  –H 

Carbon       Hydrogen                      H
Atom       Atom                           Methane  

4)NH₃                                                       H  
N          +      3H         →                   H–  N–H
Nitrogen   Hydrogen                       Ammonia
Atom           Atom

Chemical bond :A force of attraction that is established between the atoms in a molecules after the sharing or transfer of valence electrons is called bond .   They are three types :
 1)Electrovalent bond or  ionic bond
2)Covalent bond  or molecular bond
3)Co ordinate covalent bond
1)Electrovalent bond or ionic bond :The bond which is formed by the transfer of valence electrons between atoms is called electrovalent bond or ionic bond .For example : bond between  NaCl ,MgCl₂ ,K ₂O etc

2)Covalent bond :The bond which is formed by the mutual  sharing of equal valence electrons between same or different atoms  is called covalent bond or molecular bond .For example: Bond between CH₄ ,H₂O,NH₄ ,H₂ ,O₂ etc .       It is three types :
i)single covalent bond :In covalent bond if one electron is contributed by each atoms is called single covalent bond .It denoted by  -
ii)Double covalent bond :In covalent bond if two electrons are contributed by each atoms is called covalent bond .It is denoted by  ＝
iii) Triple covalent bond :in covalent bond if three electrons are contributed by each atom is called triple covalent bond .It is denoted by ≡

3)Co ordinate covalent bond :The bond in which an atom share its electrons with another  atom but second atom accept electrons but does not share or only one side sharing  is called co ordinate covalent bond .It is denoted by →

ii)NH₄

 Molecular formula :The symbolic representation of molecules of substance which show actual number of atoms present in the molecules is called molecular formula or chemical formula .For example :i) Magnesium chloride =MgCl₂, Sodium sulphate =Na₂(SO₄ ) etc.
Ways of writing molecular formula : This method is called criss –cross method.
i)Write the symbols side by side but electropositive is written first and then electronegative .
ii)Write the valency of each atom at top of its symbol .
iii)Divide the valency numbers by highest common factor then inter change the valency of symbol .
iv)Write the  inter changed valency number to the lower of the symbol .

Molecular formula of some compounds :
Name of compounds           Molecular formula
Water =                               H₂O
Carbondixide    =            CO₂
Carbonmonoxide =         CO
Ammonia              =        NH₃
Castic soda                         =    Na(OH)
Castic Potash                     = K(OH)
Methene                             = CH₄
Calcium carbonate  or limestone              =Ca(CO₃)
Lime water                         = Ca(OH)₂
Lime                                      ₌ CaO
Hydrochloric acid            =HCl
Sulphuric acid                   H₂(SO₄)
Nitric acid                           =H(NO₃)
Carbonic acid                     =H₂(CO₃)
Acetic acid                          =CH₃COOH
Carbon sulphide              =CS₂
Nitric oxide                        =NO
Hydrogen peroxide        =H₂O₂
Iron oxide (rust)                               =Fe₂O₃
Manganese dioxide       =MnO₂
Silica(Silicon oxide )       =SiO₂
Urea                                      =NH₂-CO-NH₂
Diatomic elements         =H_2,O_2,N_2,Cl_2,Br_2,I_2,F_2,

2n² rule :The rule that gives the maximum number of electrons present in the shell is called 2n²   rule .For example :
i)K- shell = 2n²  
               = 2 x1²  =2 electrons.
ii)L- shell  = 2n²
           =2x 2²    = 8 electrons
iii)  M  -Shell =  2n²
                       = 2x 3²  =18 electrons
Name of shell                                  Number of shell
K  =                                                         1
L  =                                                         2
M  =                                                       3
N=                                                          4
O  =                                                        5
P  =                                                         6
Q   =                                                       7

Differences between shell and sub shell .

Shell	Sub shell
i)A circular path on which electrons revolute around the nucleus is called shell . ii) It is denoted by K,L,M,N,O,P,Q	i)A part of shell is known as sub shell .ii) It is denoted by s,p,d,f

Difference between orbit and orbital

Orbit	Orbital
i)A circular path on which electrons revolute around the nucleus is called shell . ii)All orbit are circular and disc like .	i)The region around  nucleus in which probability of finding the electrons  maximum is called orbital. ii)Different orbital have shape and half filled or full filled orbital more stable than other .

Electronic configuration :The systematic  distribution of electrons according of their shell and sub shell is called electronic configuration . 

Variable valency :The element which has more than one valency is known as element of variable valency . It is generally  denoted by ous and ic form in which ous show lower valency and ic show higher but ic is stable than that of ous form . .For example ferrous have 2 and ferric have 3 valency . 

 Note :
Metal =Valence electrons :1,2,3 For example :Na, K
Non Metal= Valence electros:5,6,7  for example :Cl, O, Br
Metalloid = valence electrons :4 ,For example :Si, Ge, As, Te
Inert gas : valence electrons :8  For example :Ne ,Ar, Kr ,xe, Ra
N. of group : Total valence electrons i.e.  IA ,IIA ,IIIA group
N. of  period =: N. of shell
Valency :valence electron 1=1 ,2 =2,3=3,4=4,5=3,6=2,7=1,and 8=0 valency

1.)Atomic number of Na is 11 and oxygen is 8 respectively .Answer the following questions on the basis of that .
i)Write the electronic of Na, and  O .
ii)Write name the group of Na and O ?
iii) Write name the period of Na,and O ?
iv)Write valency of Na and O?
v)Which one is metal and Non metal ?
i)Na =11
1s² ,2s² ,2p^6, 3s¹
 K          K        L
ii) O=9
1s², 2s², 2p⁴
K           L
ii)Na =IA group
   O=  VIA group
iii)Na =3^rd period
     O =2^nd period
iv) Na =1 valency
     O =   2 valency
v)Na =metal
 O = Non metal

Nuclear Stability
The nucleus of any atom is composed of protons and neutrons. But ,When the ratio of protons and neutrons in the nucleus is 1, (n⁰/p⁺ =1) or more than 1, (n⁰/p⁺ >1) the nucleus is unstable. These elements are trying to move from unstable state to stable state by emission  powerful radiation. This is called  Nuclear Stability or radioactive emission. (Rediodharmi utsarjan) Generally, the nucleus of elements with high atomic number i.e.more than 80 is unstable. 

Radioactive elements
The unstable atoms emit powerful radioactive radiation called alpha (a), beta (B) and gamma ( ) to achieve stability. These types of elements are called radioactive elements.

            Or

 The element that can emit radioactive radiation is called radioactive element. Examples of radioactive elements are uranium, plutonium, thorium etc.

 Radioactive emission:
The process of emitting radioactive radiations from radioactive elements is called radioactive emission.
Or
The process of spontaneous emission of powerful alpha (ᾳ), beta (ꞵ) and gamma (y) radiations from the radioactive elements is called radioactive emission.
The discovery of radioactive  and radioactivity was made in 1896 by the French scientist Henri Becquerel
There are three primary forms of radiation:
i)Alpha (ᾳ) radiation
ii)Beta (ꞵ) radiation
iii)Gamma (y) radiation

i)Alpha particle(ᾳ):
The particles that consist of two protons and two neutrons bound together a particle identical to a helium-4 nucleus are alpha particles (ᾳ). A nucleus with too many protons causes repulsion between these like charges. To reduce this repulsion, the nucleus emits an a-particle. Examples of this can be seen in the decay of americium (Am) to neptunium (Np). An alpha particle always has a charge of +2, due the presence of two protons. Alpha-particles have very low penetration ,the outside layer of the human skin can block these particles.

ii)Beta particle(ꞵ):
The electron or positron produced from the nucleus is called beta particle. A nucleus with too many neutrons causes of conversion of neutrons into electrons called beta particle.
It may have positive or negative charge. It has more penetration power than alpha particle. The process production of electron from the nucleus is called beta decay.
Beta particles (B) have a higher penetration power than alpha particles. They are able to pass through thicker materials such as paper. During beta decay, the number of neutrons in the atom decreases by one, and the number of protons increases by one, therefore the number of protons before and after the decay is different, the atom changes into a different element.

iii)Gamma radiation(y)
 An
 An
 An extremely high-frequency radioactive radiation consisting of high-energy photons  is called Gamma radiation or gamma ray.It is also called electromagnetic waves. Gamma decay reactions occur if the energy of the radioisotope's nucleus is too high, and the resulting atomic number and the atomic mass remains unchanged during the course of reaction.
It was first discovered by a French chemist and physicist, Paul Villard in 1900. It was named gamma ray by Rutherford in 1903. Gamma radiation has no mass or charge. This type of radiation is able to penetrate most common substances, including metals.

Nuclear energy :-The energy produced from nuclear reaction in nuclear power plant is nuclear energy .Nuclear energy are produced by two methods, in both methods some mosses is lost during reaction and loss of mass according to E=mc² is converted into light and heat energy .Which is used to boil water ,to run the steam engine and to generate electricity .
Sign
  ₁ H¹  = Free proton or protium ,  
  ₁H² =deuterium ,   
₂He³ =Light helium or tritium, 
 ₂He⁴ =Helium , 
v⁰=neutrino i.e. Neutrino is  a sub atomic particle is very similar to electron but has no electrical charge.
₀ɤ⁰ =gamma ray or photon i.e During reaction loss of hydrogen convert into gamma ray and gamma ray into photon and photon into light and scatter on the universe from outer layer of sun is called corona after millions of years .Photon is a descrete  packet of energy associated with  electromagnetic radiation.
₁e⁰ or e⁺ or ꞵ⁺= Positron=Positron is positively charged electrons i.e.mass and charge of positron is equal to mass and charge of electron but nature are opposite

i)Thermo-nuclear fusion reaction :- The nuclear reaction in which two light nuclei ie. Hydrogen combine to form heavy nuclei ie. Helium with liberation of large amount heat and light energy is called thermo nuclear fusion reaction .In this reaction large amount heat and light is produced than that fission reaction ,high pressure and high temperature is required ,it is not chain reaction .For example : the energy produced from sun and hydrogen are based  on the fusion reaction .

Or
4 ₁H¹                   ₂He⁴ +2 ₁e⁰+2 ₀v⁰+2₀ɤ⁰

ii)Thermo-nuclear fission reaction:- The nuclear reaction in which an unstable nucleus of heavy atom ie.uraniun-235 split up into two medium size of nuclei ie. Barium and krypton with liberation of large amount heat and light energy is called thermo nuclear fission reaction .In this reaction less amount of light and heat energy is produced than that of fusion reaction ,it is chain reaction ,high pressure and high temperature is not required .This reaction is carried out by bombarding the heavy nuclei with neutrons. For example :Atom bomb is  based on fission reaction .

Uses of Nuclear Energy
i)It is used by developed countries to produce electricity.
ii)It is used to purify drinking water, food, medical equipment, etc.
iii) Nuclear energy is also used to treat various types of diseases like cancer.
iv)It is used for making Nuclear Bomb.

.Unit -15    

                       Chemical reaction

Chemical reaction :-The exchange ,combustion or decomposition that occurs in the molecules of substances during a chemical change is called chemical reaction . It is divided into two parts :
i)Reactant :The substance which takes part in chemical are called reactants .They are always  written in the left side of the chemical equation .
ii)Product :The substance obtained from a chemical reaction are called product .They are always written in the right side of the chemical equation .

Word equation :The chemical equation in which the names of substance and products are expressed in the form of word is called word equation . For example :
 i)  Hydrogen + Oxygen    _→       water
ii) Magnessium + Oxygen   _→    Magnesium oxide
iii)Calcium carbonate        _→  Calcium oxide +Carbon dioxide

Chemical equation : The symbolic representation of the chemical reaction by writing the symbol and formula is called chemical equation. For example:
1)Sodium + Oxygen    _→        Sodium oxide
4Na     `+ O_{2        →}      2Na₂O
2)Magnesium + Oxygen       _→  Magnesium oxide
2Mg     +          O_{2       →}          2MgO
3)Hydrogen + Chlorine      _→   Hydrogen chloride
H₂   +  Cl_{2                                →}         2 HCl
4)Zinc +Chloride      _→    Zinc Chloride
Zn  + Cl_2   →          ZnCl₂
5)Nitrogen + Hydrogen       _→   Ammonia
N₂      +     2H_{3     →}       2NH₃
6)Iron + Oxygen  _→  Iron oxide
Fe   +  O_{2     →}               Fe₂O₃
7)Magnesium +Nitrogen   _→   Magnesium Nitride
3Mg +  N_{2   →}          Mg₃N₂
8)Carbon dioxide +Water   _→    Carbonic acid
  CO₂        +H₂O   _→   H₂CO₃
9)Aluminum + Oxygen _→     Aluminum oxide
Al  +O_{2                  →}    Al₂O₃
10)Aluminum + Chlorine    _→      Aluminum Chloride
2Al    + 3Cl_{2         →}         2AlCl₃
11)Ammonia +Hydrochloric acid    _→  Ammonium chloride
NH₃       + HCl        _→     (NH₄)Cl
12)Nitrogen +  Oxygen    _→    Nitric oxide
N₂     + O_{2   →}      2NO
13)Calcium oxide + Water    _→  Calcium hydroxide
CaO     +  H₂O     _→    Ca(OH)₂
14)Sodium oxide   +Water       _→   Sodium hydroxide
Na₂O   +H₂O       _→    2Na(OH)
15)Magnesium oxide +Water  _→  Magnesium hydroxide
16)Ammonium oxide +Water  _→ Ammonium hydroxide
 (NH₄)₂O    + H₂O       _→  2(NH₄)(OH)
17)Water        _→    Hydrogen   + Oxygen
2H₂O             _→    2H₂     + O₂ 
18)Potassium chlorate    _→  Potassium chloride + Oxygen
2K(ClO₃)    _→    2KCl     + 3O₂
19)Calcium carbonate   _→  Calcium oxide +Carbon dioxide
Ca(CO₃)    _→    CaO     + CO₂

20)Magnesium oxide  _→  Magnesium +Oxygen
2Mg O       _→     Mg + O₂
21)Hydrogen peroxide   _→    Water + Oxygen
2H₂O_{2       →}               2H₂O +O₂
22)Calcium bicarbonate  _→  Calcium carbonate +Carbon dioxide +Water
Ca(HCO₃)_{2           →}   Ca(CO₃) +CO₂    +H₂O
23)Magnesium bicarbonate     _→  Magnesium carbonate +Carbon dioxide +Water
Mg(HCO₃)_{2         →}    Mg(CO₃) +CO₂  +H₂O
24)Zinc +Sulphuric acid       _→    Zinc sulphate +Hydrogen
Zn +  H₂(SO₄)      _→    Zn(SO₄ )  +   H₂
25)Zinc  + Hydrochloric acid  _→  Zinc chloride + Hydrogen
Zn       +   2HCl           _→       ZnCl₂   +  H₂
26)Potassium + Nitric acid   _→ Potassium Nitrate +  Hydrogen
 2 K  + 2H(NO₃)  _→   2K(NO₃)    +  H₂
27)Iron + Copper Sulphate   _→ Iron Sulphate +Copper
2 Fe +3 Cu(SO₄)      _→    Fe₂(SO₄)₃   + 3Cu
28)Aluminum  + Hydrochloric acid  _→   Aluminum chloride +Hydrogen
2 Al      +6 HCl           _→   2AlCl₃  + 3 H₂
29)Magnesium + Copper Sulphate    _→  Magnesium Sulphate + Copper
Mg + CuSO_{4       →}    Mg(SO₄)  + Cu
30)Sodium + Water       _→  Sodium hydroxide + Hydrogen
2 Na +2H₂O          _→    2Na(OH) +H₂
 31)Magnesium+ Water     _→   Magnesium hydroxide +Hydrogen
 Mg + H₂O      _→   Mg(OH)₂          +H₂
32)Zinc +Silver Nitrate  _→    Zinc Nitrate +Silver
Zn + 2Ag(NO₃)        _→    Zn(NO₃)₂  +2Ag
33)Calcium +Water       _→   Calcium hydroxide +Hydrogen
 Ca +2H₂O      _→     Ca(OH)₂ +H₂
34)Aluminum +Sulphuric acid      _→  Aluminum Sulphate+ Hydrogen
2Al+3 H₂(SO₄)      _→                                  Al₂(SO₄)₃ +6H₂
35)Copper +Silver Nitrate    _→    Copper Nitrate +Silver
  Cu +  2Ag(NO₃)           _→    Cu(NO₃)₂ +2 Ag
36)Calcium Carbonate +Hydrochloric acid   _→   Calcium Chloride +Carbon dioxide +water
Ca(CO₃) +2HCl     _→  CaCl₂ +CO₂ +H₂O
37)Sodium Hydroxide +Hydrochloric acid    _→      Sodium Chloride + Water
2Na(OH)+2HCl        _→     2NaCl +H₂O
38)Sodium Oxide +Hydrochloric acid    _→         Sodium Chloride +Water
Na₂O   +2HCl          _→    2NaCl +H₂O
39)Calcium Oxide +Sulphuric acid  _→   Calcium Sulphate +Water
CaO +H₂(SO₄)   _→     Ca(SO₄)+H₂O
40)Magnesium Oxide +Hydrochloric acid   _→    Magnesium Chloride +Water
MgO+2HCl         _→     MgCl₂ +H₂O
41)Potassium Hydroxide + Hydrochloric acid    _→   Potassium Chloride +Water
2K(OH)+2 HCl         _→    2KCl +H₂O

Types of reaction according to heat :There are two types of reaction according to heat :
1.)Exothermic reaction : The reaction in which heat is released to the surrounding  is called exothermic reaction. For example :
i )C + O _{2                      →}                                 CO₂  +Heat
ii) C₆H₁₂O₆ +6O_{2            →}           6CO₂ + 6H₂O Energy +Heat
2.)Endothermic reaction :The reaction in which heat is absorbed from the surrounding is called endothermic reaction .For example :
i)Ca(CO₃)  + Heat             _→  CaO +CO₂
ii)2K(ClO₃)   +Heat         _→   2KCl + 3O₂

Balanced chemical equation : The chemical equation written by balancing the N. of atoms of element on both sides of reactants and products is called balanced chemical equation .For example :
2H₂ + O_{2      →}                            2H₂O
Advantages  or information can be obtained from of balanced chemical reaction : Following information can be obtained from balanced chemical equation :
i)The types of chemical equation
ii)Names of reactants and product
iii)Molecular formula  or symbols of reactants and products
iv)N. of atoms and molecules of reactants and products .
Limitation of a balanced chemical equation :The information which can not show a balanced chemical equation are called limitation of balanced chemical equation .They are as following :
i)Rate of chemical equation .
ii)Concentration of reactants .
iii)Duration of chemical reaction .
iv)Conditions necessary for chemical reaction .

Importance of Chemical reaction in our daily Life :
i.It  helps plants in preparation of food during photosynthesis.
ii.It helps  to solve crimes by collecting blood and tissue  sample.
iii. Many medicine ,drugs, paints, fertilizer, etc. are manufacture by using chemical reaction.
iv)Chemical reaction helps our nerves to work by pumping sodium and potassium .  

Catalyst :A chemical substance which changes the speed of rate of chemical reaction with out changing itself is called the catalyst . There are 2 types of catalyst :
i)Positive catalyst :A catalyst which increase the rate of chemical reaction is called positive catalyst .i.e. Manganese dioxide acts as positive catalyst in a decomposition reaction of potassium chlorate .
i.Potassium Chlorate     _→ MnO₂    Potassium Chloride + Oxygen 
2K(ClO₃)    _→  MnO₂        2KCl +3O₂
ii)Negative Catalyst :A catalyst which decrease the rate of chemical reaction is called negative catalyst .i.e. Glycerin acts as negative catalyst in decomposition of hydrogen peroxide .
2H₂O_2  →          Glycerin      2H₂O  + O₂
 
Characteristics of catalyst:
i.Catalyst  do not take part in chemical reaction between reactants but they increase or decrease rate of chemical reactions.
ii. Catalysts remain chemically unchanged without being consumed during reaction.

Unit :- 16          

                      Some Gases (H₂,O₂,N₂ )

A:- Hydrogen gas (H₂)
1)Introduction: The symbol of hydrogen gas is H, atomic N. 1, atomic mass 1a.m.u. ,molecular formula H₂, and valency is 1 .It was discovered by Henry Cavendish .It is generally found in volcanic eruption ,petroleum and organic substances i.e. hydrocarbon.

Fig. Molecular structure of H₂ gas

2.)General preparation of H₂ gas .
i)By electrolysis of water :Hydrogen gas can be prepared from decomposition of water by electrolysis .

3.)Method of lab. preparation of H₂ gas :
i.)Apparatus required :Wolf bottle ,Thistle funnel ,delivery tube, gas jar, beehive self, heating apparatus.
ii)Chemicals required: zinc pieces, Sulphuric acid
iii)Principle:- H₂ gas can be  prepared by heating zinc pieces with dil. Sulphuric acid .

Reaction :
Zinc + dil. Sulphuric acid     →  Zinc sulphate + Hydrogen gas    
Zn + H₂(SO4)   →         Zn (SO₄)  +H₂

iv.)Precaution :
i)end of the thistle funnel should be dipped under acid layer.
ii)Apparatus should be made airtight.
iii)Pure Zinc is not used for the prepartion of gas as it reacts very slowly  with dil. H₂(SO₄) .Impurities increase the rate of reaction.
v)Test  of  H₂ Gas:
When a burning splinter is introduced in a gas jar containing if splinter goes out while the gas burns a the mouth of the gas jar with pop sound and gas is hydrogen gas.

4.)Properties :
Physical properties :
i)It is colourless ,odourless, and test less gas .
ii)It is the lightest gas .i.e. 22.2 liters of H₂ gas of wt only 2 gm .
iii)It is insoluble in water .
iv)It has no effect on an indicator .
Chemical properties:
i)When Hydrogen gas is burn in air ,water is obtained .
2H₂   +   O₂   →      2H₂O
ii)When Hydrogen react with halogens i.e. Cl₂, Br₂,I₂,F₂,etc. and their respective halides are formed .
H₂   +  Cl₂                  →                            2HCl        
H₂     +   Br₂                 →                        2HBr       Hydrogen halides
H₂      +I₂                     →                           2HI
iii)When hydrogen react with Nitrogen at high temperature and high pressure Ammonia gas is obtained .This process is Haber’s process .
N₂  +3H₂       →       2NH₃
iv)When hydrogen combine with vegetable oil ,vegetable ghee is obtained .This process is known as hydrogenation .
H₂   +  vegetable oil    →   vegetable ghee

5.)Uses of H₂ gas :
i)It is used in manufacture of ammonia ,which is used making fertilizer .
ii)It is used for making vegetable ghee .
iii) It is used as fuel in rocket .
iv)It is used in welding and cutting  metal .
6.)Nascent Hydrogen :The newly born Hydrogen which is produced at the time of chemical reaction or very active hydrogen or hydrogen atom is called Nascent Hydrogen. It is denoted by H .Due to its highly reactive properties it immediately combine to Hydrogen to form Hydrogen molecules .

B .   Oxygen(O₂) gas
1.)Introduction :The symbol of oxygen is O,atomic N. 8,atomic weight 16 a.m.u., molecular formula O_2, and valency is 2 .It was first prepared by Joseph Priestley.It was named oxygen by Lavoisier

It is generally found in nature both free in air and combined state i.e. in water ,dissolve state ,in mineral combined state, and about 72% in our body as compound .

Fig. Molecular structure of H₂ gas

2.)General preparation of O₂ gas :
i)By Metal oxide :When metal oxide are heated and O₂ gas is produced .
2MgO    →      2Mg + O₂
2HgO    →      2Hg + O₂
2Ag₂O  →    4Ag + O₂
ii)By electrolysis of water :- Oxygen gas can be produced from decomposition of water by electrolysis method .
  H₂O   →    H⁺       +   (OH)^-
Reaction at cathode :
H⁺   +  e^-   →       H
4H            →    2 H₂
Reaction at anode :
 (OH)^-    →       (OH) + e ^–
4(OH)   →      H₂O  +O₂

3.)Method of lab .preparation of O₂ gas :
A)By heating method :
i)Apparatus required :Hard glass test tube, delivery tube , gas jar, beehive self, heating apparatus.
ii)Chemical required : Potassium chlorate ,Manganese dioxide .
iii)Principle : O₂ gas can be prepared by heating K(ClO₃) in presence of MnO_2..

Reaction :
Potassium chlorate →    Potassium chloride + Oxygen
2K(ClO₃)    →       2KCl     +3O ₂

iv)Precaution :
i)The apparatus should made air tight.
ii)The manganese dioxide used as catalyst should be in pure form.
iii)The gas jar should be completely filled with water.
iv) Heat should be provided continuously with low flame strength.
b)Without heating method :
i)Apparatus required : Conical flask, thistle funnel, delivery tube ,Gas jar, Beehive self,
ii)Chemical required :Hydrogen peroxide, Manganese dioxide .
iii)Principle :O₂ gas can be prepared by  decomposition  Hydrogen peroxide in presence of manganese dioxide.

iii)Reaction :

Hydrogen peroxide   → ^MnO2  water + Oxygen

2H₂O₂ →  ^MnO2    2H₂O + O₂

 iv.)Precaution :
i)End of the thistle funnel should be dipped under acid layer.
ii)Apparatus should be made airtight.
iii)The manganese dioxide used as catalyst should be in pure form.
Test of O₂ gas :When burning splinter is introduced in a gas jar containing  gas if gas burn more brightly and gas is Oxygen gas .because it is supporter of combustion.

4.)properties :
Physical :
i)It is colourless, odour less, and test less gas .
ii)It is slightly soluble in water i.e. about 3%
iii)It is does not burn but support to burn i.e. supporter to combustion.
Chemical properties:
i)When oxygen is burn with hydrogen, water is obtained . 
  2 H₂ + O₂       →      2H₂O
ii)When oxygen react with carbon dioxide is obtained .
   C  + O₂     →      CO₂
iii)When Oxygen combine with Nitrogen during lighting discharge  Nitric oxide is obtained .
N₂       +  O₂  →  ^Lighting       2NO    (Nitric oxide)
iv) When oxygen react with metal their respective metal oxide or base is obtained .
2Na + O₂     →        Na₂O
2Mg + O₂        →    2MgO              Metal oxide or base
K +      O₂         →    K₂O
Fe  +   O₂        →   Fe₂O₃ (rust) 

5.) Uses of Oxygen:
I) It is used by living being for respiration .
ii)It is used for artificial respiration in hospital .
iii) Miners , Mountains, and sea divers carry oxygen cylinder with them for respiration .
iv)Liquid O₂ is used as a part of fuel in rocket and jet plane to make burning fuel .
6)Ozone gas and ozone layer(O₃): When oxygen molecules absorb high energy of solar radiation and it dissociate into nascent oxygen then nascent oxygen combine with an oxygen molecules and a new molecule is formed is known as ozone gas
i-O_{2       →} ^{UV Rays}     O+O(Nascent Oxygen)
ii-O₂ + O     _→     O₃ (ozone gas)
Ozone gas is found upper most layer of stratosphere as a layer of pale bluish gas (gas) is called ozone layer or ozonosphere.
The region in the atmosphere where amount of ozone has been reduced drastically is called ozone hole. For example :Ozone hole has been detected over the region of Antarctica in 1980.

Advantages or protection of ozone layer:
i)Ozone layer play an important role to keep weather and temperature of the balanced .
ii)The ozone layer absorbed about 99% of the harmful ultra violet ray coming from the sun.
iii)Ozone layer help to preserve the aquatic and terrestrial ecosystem on the earth.

Causes(Chemicals) of depletion of ozone layer:
i)Chlorofluorocarbon  (CFCl_{3 ,}CFCl_{12 and}CFCL₁₃): American scientist Thomas Miez is the inventor of CFC_s .It is major causes of ozone layer depletion.
-CFCl_{3      →}  ^{UV radiation}     CFCl₂+Cl(Nascent  Chlorine)
-Cl +O_{3    →}            ClO +O_2
-2ClO       _→         2Cl+O₂
Uses or advantages of CFC_s gas: -It very cheap ,non –toxic, and non flammable so it can be used in refrigerator, aerosol, spray can, plastic manufacturing etc.
-It act as cooling agent as well as solvent.
ii)Methyl bromide(CH₃Br)
iii)Chloroform(CHCl₃)
Process of depletion of ozone layer:  When the gases like CFC_s,CO,CH₃Br,oxides of nitrogen etc. reach into stratosphere ,they are decomposed by ultra violet radiation and chlorine is formed .This chlorine help to decompose ozone and depletion of ozone layer takes place.
Effects of depletion of ozone layer:  Due to depletion of ozone layer more ultra violet radiation reach on earth’s surface ,that cause of following effects:
i-)Effects on health of human being: due to depletion of ozone layer in human being ultra violet rays causes of various diseases i.e. skin cancer ,breast  cancer, blood cancer, Blindness ,damage to immune system, affect to DNA and causes of mutation.
ii-)Effects on plants and animals :  Due to depletion of ozone layer in plants and animals ultra rays cause of hamper of growth and development animals and plants, productivity of crops reduced, destroy protein content and chlorophyll, affects fertility of animals, larva, and eggs of aquatic and amphibian and eye cancer in cattle.
iii-)Increase in temperature :  due to depletion of ozone layer more ultra violet radiation enters the earth’s surface then due to more radiation more heat accumulates and green house effect  increases ,as result the temperature of earth increases or causes of global warming.
 Protection of ozone layer:
i)Reducing and controlling the emission of CFC_s.
ii)Uses of nitrogen fertilizer should be reduced.
iv)Generating awareness about the ozone layer depletion in people.

C. Nitrogen Gas:
1.Itroduction : The symbol of Nitrogen is N, atomic N.7,atomic weight 15 a.m.u., molecular formula N_2, and valency is 2,and3 .It was discovered by Daniel Rutherford. It was named azote by Lavoisier, because it does not support for combustion and respiration .
It is generally found in nature both free in air and combined state i.e. in protein, and  Nitrate salt.

Fig. Molecular structure of H₂ gas

2.Method of general preparation of N₂ gas:
i.)By heating of ammonia with copper oxide :When ammonia gas is prepared over heated copper oxide ,Nitrogen gas is obtained .
3CuO + 2NH₃   →          N₂ +3Cu +3H₂O
ii)By heating copper oxide in air :At first air is passed through lime water to eliminate  CO₂ ,then passed through conc. H₂( SO₄) to revolve moister and through cooper gauze to form CuO and from remaining as N₂ gas is obtained .
Cu +O₂      →          2CuO
3.Lab preparation of N₂ gas :
i)Apparatus required :Round bottom flask ,Delivery tube, Thistle funnel ,Gas jar, Beehive self, heating apparatus .
ii)Chemical required :Sodium Nitrite ,Ammonium Chloride,
iii)Principle :N₂ gas is prepared by heating Na(NO₂) with (NH₄ )Cl.

Reaction :
Na(NO₂) + (NH₄)Cl  →         NaCl +2H₂O +N₂ 
iv)Precaution:
i)End of the thistle funnel should be dipped under acid layer.
ii)Apparatus should be made airtight.
iii)Ammonium chloride is volatile so before heating solution is made.
iv)Mixture of Ammonium chloride and SodiumNitrite should be gently heated.
 v)Test of N₂ gas :If a burning splinter  is introduced inside the gas jar then they neither combustible nor support  for combustion and gas is N₂.

4.Properties :
A) Physical properties :
i)It is colourless ,odourless and test less gas .
ii)It is lighter than that of air .
iii)It is slightly soluble in water .
iv) It is neither combustible nor supporter of combustion .
B)Chemical properties :
i)When magnesium  is react with Nitrogen ,magnesium Nitride is obtained .
3Mg + N₂      →    Mg₃N₂
ii)When Nitrogen is react with hydrogen under high temperature and high pressure ,ammonia gas is obtained .
N₂     +   3 H₂  →^{high pressure/temp}     2NH₃
iii)At high temperature during lighting when Nitrogen react with Oxygen Nitric Oxide is obtained .
N₂       +   O₂   →  ^lighting      2NO
5.Uses of N₂ gas :
i)It is used for making different fertilizer .
ii)It is used for making Nitric acid ,and ammonia gas .
iii)It is filled in filament to remove vaporization inside filament .

Unit :- 17              

         Metals and Non-Metals 

Metal :-The elements which have  a tendency to loss electrons and form cat ion are called metal .For example :Mg, Na, Ca, Al etc.

Properties of metals:
Physical properties:
i)Most of metals are solid at ordinary temperature ,except mercury ,it is found in liquid state .
ii)Most of metals are generally hard ,except Na, K, Li, they are soft .
iii)Metal posses metallic luster (shining)
iv)Metals have generally high density ,except Na, K ,Li.
v)Metal posses ductile property (i.e. can be change into wires)except Na, K, Li.
vi)Metals are generally good conductors of heat and electricity .
vii)The boiling and melting point of metals are high ,except Na, K, Li.
viii)Metals atoms generally contains 1,2,3,electrons to their valence shell .
ix)Metals are generally electropositive in nature because loss their valence electrons.
x)Metals possess malleability (i.e. can be beaten in thin plate)

Chemical properties:

Non metal :The element which have a tendency to loss electrons and form anions are called non metal .For example :H_{2 ,}O_{2 ,}Cl_2, Br_2, N₂ etc.
Properties :
i)Non metals are generally found in all three states i.e. solid For example: Carbon ,liquid For example: Bromine ,gas For example :Hydrogen ,Oxygen, Nitrogen etc.
ii)Non metals are generally soft and light ,except carbon in the form of diamond and graphite .
iii)Non metals have generally very low melting points ,except carbon.
iv)Non metals have generally very low density ,except iodine.
v)Non metals are generally not ductile ,except carbon.
vi)Non metal are not malleable .
vii)Non metal are generally brittle (i.e. break  when force is applied )
viii)Non metals are non conductor of heat and electricity .
ix)Non metals generally contains 4 or more than 4 electrons to their valence shell.

Metalloid :The elements which show properties of both metals and non metal are called metalloid .For example :Boron (B),Silicon(Si),Germanium (Ge), Arsenic (As) ,Antimony (Sb),and Tellurium (Te) etc.
Properties of metalloid :
i)They are poor conductor of heat and electricity .
ii)They posses metallic luster .
iii)They form alloys .
iv) They are neither malleable nor ductile .
v)They are generally solid in state .
vi)They are brittle in nature .
v)They can conduct heat and electricity better than non
metal less than metal .
Uses of metalloids :
i)Tellurium is used in manufacture of electric resistors, rubber, ceramics ,glass .
ii)Antimony is used in several alloys i.e. glass .
iii)Silicon is used in the manufacture of electronic devices .
Alloy: A homogenous mixture of two or more than metal or non metal are called alloys .For example :Brass .
Properties of alloys :
i)They are generally harder than their components .
ii)They are good conductors of heat and electricity .
iii)They are malleable and ductile .
iv)Alloys increase the strength of metal .

Roles of some metals in human body :
1.)Roles of Zinc in human body :It is found in small amount inside the body of organism .i.e. in adult about 2-3 gm Zn is found in cell , tissue, bone, retina, and abdomen.
Sources :
i.)Seeds of plants like pumpkin sunflower, legumes, mushroom almond, cashew walnut etc
ii). Dairy products, meat, fish, egg etc.
Functions:
i.Zn is needed for the body's defensive system to proper work
ii. Zn plays a role in cell division, cell growth. wound healing and breakdown of carbohydrates.
iii. Zn is needed for the sense of smell and taste during pregnancy, Infancy, and in childhood the body needs Zn to grow and to develop properly.
iv. Zn may reduce the risk of bacterial and viral infection and reduces the risk of becoming sick with common cold, pneumonia, diarrhoea.
v. Zn enhances pituitary hormone function.
vi. It helps in the synthesis of genetic material, DNA, protein etc. in the cell.
vii)It support the body to make healthy .
viii)It act as a cofactor for enzyme
ix)It help for physical functions in the bone ,kidney and
brain.
Effects due to deficiency  or irregularity:
i. Hair loss
ii. Reduction in taste and smell
iii. Laziness/fatigue
iv. Diarrhoea and weight loss
v. Slow healing of wounds and cuts.

2.)Roles of Sodium  in human body :Sodium and potassium ions are found out side as well inside of the cell .
Sources:
i.Common salt [NaCI] is the main source  of sodium in human body.
ii. Sodium is also obtained from meat and egg.
Functions:
1It helps to balance the amount of water and salts inside and outside the human body cells
2. It regulates the efficiency of nerves and muscles.
Effects  due to deficiency or irregularity of Sodium
i.It causes disease called  hyponatremia.
ii. It causes muscular spasms.
iii. It can cause vomiting, dizziness, unconsciousness and even death.
3.Roles of  Potassium in human body : Sodium and potassium ions are found out side as well inside of the cell .
Sources:
i.Foods like soyabean, vegetables and dairy products.
ii. Fruits like banana, avocado and young bamboo shoots.
Functions
i.Potassium maintains the water balance and osmotic pressure.
ii. Potassium maintains acid-base balance.
iii. Potassium helps to metabolize carbohydrates and proteins
iv. Potassium regulates neuromuscular efficiency.
Effects  due to deficiency or irregularity of Potassium
i.It causes disease called hypokalemia.
ii. It causes high blood pressure, constipation, weakness in body and weakens the muscles.
3.Roles of  Iron in human body : Iron is present in all cells in the human body and help carry oxygen to tissues to lungs.
Sources:
i.Spinach, grains, broccoli, seeds of plants etc.
ii. Meat and fish
Functions:
i.Iron  present in haemoglobin of blood helps in oxygen transport.
ii. DNA synthesis.
iii. It helps to improve immunity and regulates energy production.
Effects  due to deficiency or irregularity of iron
1. It causes anaemia.
2. It causes fatigue and difficulty in respiration.

Harmful effect of mercury :
i)It is causes of depression .
ii)It is causes of memory loss .
iii)It is causes of heart attack .
iv)It is causes of skin discolouration
Sources:
i.Volcanoes,forest fire,fossils i.e. coal and petroleum.
ii.Fish and shellfish contaminated with methylmercury.
Harmful effect of Lead :
i)It is causes of anaemia.
ii)It is causes of hyper tension.
iii)It is causes of headache and stomach pain.
iv)It is also may lead to coma and death .
Sources:
i) Lead based paint, contaminated soil.
ii)Ceramics, pipes, gasoline, battery, cosmetic etc.

Unit :- 13                  

                           Carbon and its compounds

Organic chemistry :The branch of chemistry concerned with the compounds of carbon is called organic chemistry .
Inorganic chemistry: The branch of chemistry concerned with the compound of elements other than carbon is called inorganic compound . 
Differences between organic and inorganic compound :

Organic compound	Inorganic compound
i.)The compounds of carbon other than oxides of carbon ,carbonates, bicarbonates, and carbides are called organic compounds .   ii.)Organic compounds having low melting and boiling points . iii.)Organic compounds burn easily .i.e. Ghee, alcohol  iv)These are formed by covalent bond. v.)Organic compounds are insoluble in water .	i.)The compounds other than compounds of carbon except oxides of carbon, carbonates ,bicarbonates ,and carbides are called inorganic compounds. ii.)Inorganic compounds having high melting and boiling points iii)Inorganic compounds do not burn easily . i.e. salt iv)These  are formed by electrovalent bond. v)Inorganic compounds are soluble in water .

Carbon :Its symbol is C ,atomic number 6,atomic weight 12 and valency 4 .It is derived from Latin word carbo  which means charcoal .It is found in the nature various form i.e. CO₂ ,Coal , charcoal, graphite ,diamond  etc.
Sources of carbon :
i.)It is found in atmosphere in the form of CO₂ .
ii)It is found in all living being in the form of compounds .
iii.)It is found in the form of carbonate, and bicarbonate  compounds .
iv)It is found in natural hydrocarbon i.e. coal ,Petroleum, and natural gas .
Nature of carbon :  Carbon atoms has 4 valence electrons to their valence shell ,so it can loss or gain 4 electrons to become stable but the size of the carbon atom is smaller,so effective nuclear charge is strong and strongly hold valence electrons .Hence It can neither loss nor can gain electrons and can not form electrovalent bond .Therefore it form 4 covalent bond by sharing its 4 valence electrons with other atoms . 

Allotropes :The property of a pure element having same composition but found in two or more than two forms in the same state is called allotropes .For example :
                               Allotropes of carbon

Catenation: The ability of carbon to combine with another carbon atoms to long chain of or ring of different size is called catenation .

Properties of carbon :
Physical properties of carbon :
i)It is found in solid state and non metal .
ii.)It is insoluble in water .
iii)It show allotropic properties .
iv)It is generally black in colour but diamond is colourless and transparent .
Chemical properties :
i)When carbon burn with sufficient oxygen ,carbon dioxide is obtained but with insufficient oxygen carbon monoxide is obtained.
C+O₂   →     ^sufficient     CO₂
2C  + O₂    →   ^insufficient      2CO
 ii)When carbon react with steam at high temperature ,carbon monoxide and hydrogen gas or water gas
C   + H₂O   →    CO+H₂
                                 Water gas
Uses of carbon :
i.)Carbon is used as fuel .
ii.)Charcoal is used for purifying drinking water ,decolourlizing  sugar .
iii)Lamp black is used in the printers ,manufacture of polish,black paints .etc .

Hydrocarbon :The compounds hydrogen and carbon is called hydrocarbon.
Types  of hydrocarbon :They are two types :
A.)Saturated hydrocarbon :The hydrocarbon in which carbon-carbon atoms combines with single covalent bond are called saturated hydrocarbon .Its IUPAC(International union pure applied chemistry ) name is alkane  For example :

B.)Unsaturated hydrocarbon :The hydrocarbon in which carbon atoms combine with double covalent bond is called unsaturated hydrocarbon.Its  IUPAC (International union pure applied chemistry ) name is Alkene .For example :

Use of organic compound in our daily Life
i.Food: Food stuffs contains organic compounds i.e. cabohydrates ,protiens,fat, vitamins,etc. Are essential for healthy growth and development.
ii.Clothes :Fibres obtained from plants and animal are organic compounds which are used to make clothes and other necessary items .
iii.Cosmetics :Organic compounds are used as raw materials for the manufacture of cosmetic goods and soap.
iv.Medicines :Raw materials derivedd from plants and animals which contains carbon compounds are used to treat various diseases.

Unit :-19  

                    Chemical fertilizers used in Agriculture

 Nutrients for Plants:There are 17 elements which are importants for metabolism of plants :They are classified into two types on the basis of amount of minerals required by plants for metabolism :
1)Primary Nutrients or Macro-nutrients :The chemical elements required by plants in greater quantities are called macronutrients .For example :Carbon(C),Oxygen(O),
Sulpher(S),Hydrogen(H),Nitrogesn(N),Phosphorus(P),
Potassium(K) and Calcium(Ca). They help in growth and development of plants .
2)Secondary Nutrients or Micronutrients :The Chemicals elements required by plants in smaller quantities are called micronutrients .For example :Boron(B),Iron(Fe),Zinc (Zn),Magnesium(Mg),Chlorine(Cl),Copper(Cu),Nickel(Ni),and magnesium (Mg).They help in metabolic activities of plants.

Fertilizer :The substances which are added to increase the fertility of soil or  increase to  crops production are called fertilizer .
Types of fertilizers :-They are two types :
1)Organic fertilizers: The fertilizers which are obtained from dead and decomposed parts of animals and plants or their waste product are called organic fertilizer . There are also two types of organic fertilizers :-
i)Green organic fertilizers :The organic fertilizer which are prepared by cutting green plants and later which are decomposed under soil are called green organic fertilizer or green manure .These types of fertilizer mainly provides  nitrogen  to the plants in form of nitrates .
 
ii)Animal organic fertilizer :-The organic fertilizer which are prepared from dead and decayed parts of animals due to the action of bacteria and enzymes in their body are called animal organic fertilizer .It do not contain nitrogen ,phosphorus and potash but can control weeds and increases the moisture-holding capacity of the soil and increases air penetration in the soil.
Advantages of organic fertilizers :
i.)It help to Balances the soil ecosystem
ii)It help plant to make health naturally
iii)They’are all-natural .
iv)It increase the fertility of soil.
 v)It does not  affect the quality of soil.
vi)It controls environmental pollution.
 vii)Prevents from  over-fertilization
Disadvantages of organic fertilizers:
i)It requires more  time to be  prepared. so effectiveness is limited seasonally.
ii)It is insoluble in water and it is difficult to transport from one place to another place .
iii) Nutrients ratio is always unknown .

2.)Chemical fertilizers or inorganic fertilizers: The fertilizer which are made by mixing different  of chemicals substances are called chemical fertilizers .They are mainly contains nitrogen, phosphorus and calcium elements.

N.P.K fertilizers :The fertilizer containing  all three nutrients i.e. Nitrogen(N) ,Potassium (K) and calcium(Ca) essential for plants is called NPK fertilizers .It is also called complete fertilizer.
 Advantages of chemical or inorganic fertilizers :
i)Inorganic  fertilizer increase the fertility of the soil.
ii)They have special types of nutrients .
iii)They can transport easily .
iv)They are water soluble ,so plants can absorb easily .
Disadvantages of inorganic or chemical  fertilizers :
i)Inorganic fertilizer pollute the environments.
ii)Inorganic fertilizers increase the fertility of the soil.
Considering factors or  precaution  while using chemical fertilizers :
i)Before the use of chemical fertilizers, we must test the acidic or basic nature of soil.
ii)At the time of using chemical fertilizers ,we must cover our mouth and nose .
iii)we must control the flow of chemical fertilizers in sources of water .
iv)Chemicals fertilizers should be used scientifically ,in term of proper dose   and time ,because excessive use  of fertilizer can harm plants instead of better growth .

Some important inorganic fertilizers :
1.)Nitrogeneous  fertilizer :The chemical fertilizer that supply nitrogen to plants are known as nitrogeneous fertilizer For example :
i)Urea (NH₂CONH₂)
ii)Ammonium suplhate  (NH₄)₂(SO₄)
iii)Ammonium nitrate (NH₄)(NO₃)
Functions of Nitrogen :
i)It help in rapid growth in plants .
ii)It help to increase yield of growth .
iii)Sufficient nitrogen help for high rate of photosynthesis .
iv)It help in the formation of chlorophyll ,carbohydrate, and protoplasm .
Deficiency of Nitrogen :
i)Due to lack of nitrogen plants will be shorter ,leaves may be smaller and maturity of plants may be delayed too .
ii)Shortage of nitrogen will causes of yellowing of leaves .
iii) Due to lack of nitrogen rate of photosynthesis will decreases and less branching in plants .
2.)Phosphatic  fertilizer :The fertilizers that supply phosphorus to the plants are called phosphatic fertilizers .For example :
i)Calcium super phosphate
ii)Triple super phosphate
iii)Bone metal .
Functions of Phosphorus :
i)It help in early maturity in plants .
ii)It help in formation and fast growth of root .
iii)It help in formation of seeds and increase resisting diseases .
Deficiency  of phosphorus :
i)Due to lack of phosphorus flowering may be delayed .
ii)Due to lack of phosphorus rate of cell division decreases .
iii)Due to lack of phosphorus reduces diseases resistant power of the plants .
3.)Potash fertilizers :The fertilizers that supply potassium to plants are known potash fertilizers .For example :
i)Potassium chloride (KCl)
ii)Potassium sulphate  K₂(SO₄)
iii)Potassium carbonate K ₂(CO₃)
iv) Potassium Nitrate    K (NO₃)
Functions of potassium :
i)It help in the utilization of nitrogen and help in protein synthesis .
ii)It help for making healthy roots and shoots .
iii)It also help to increase resist against diseases
iv)It help to regulates the opening and closing of stomata . 
Deficiency of potassium :
i)Lack of potassium causes of poor resistance for  diseases.
ii)Lack of potassium causes of weak roots and shoots.
iii)Lacks of potassium causes of losing of leaves .

Insecticides :-The chemical substances which are used to kill harmful insect is called insecticides.
Types of insecticides :They are two types
1.)Organic insecticides :The insecticide which are containing carbon are called organic insecticides. It also contains hydrogen ,oxygen, chlorine  and, phosphorous. On the basis of chlorine, phosphorous, and  carbomate  organic insecticides are also divided into 3 types :
A)Organo –Chlorine :The organic  insecticides which contains chlorine as principle element is called organ chlorine .For example :i)DDT =Dichloro diphenyl  trichloro ethane
ii)BHC =Benzene Hexa chloride
iii)Dieldrin
iv)Aldrin
B)Organo-Phosphorous :The organic insecticide which contains phosphorous as principle elements is called Ogano-phosphorous .For example :i)Malathion  ii)Parathion
C)Carbomate :The organic insecticide which contains amino group(NH₂) as principle element is called carbomate .For example :i)Baygon   ii)Turmic
2.)Inorganic insecticide :The insecticides which are made up from minerals or inorganic compound is called inorganic insecticides. For example :i)Lead arsenate  ii)Calcium arsenate  iii)Lime sulpher   iv)Floride
It is used to protect fruits ,vegetables ,cotton etc.
Advantages of insecticides :
i)They are used to control or kill harmful insects .
ii)They also help to control diseases.
Disadvantages of insecticides:
i)Insecticides kill harmful insecticide as well as useful insecticide .
ii)They are non bio-degradable so causes of soil,air and water pollution .
Precautions in using  insecticides :
i.)Make  globes and aprons should be used while using insecticides.
ii)Insecticides should be stored and kept away from the reach of children.
iii)Before using insecticides proper training should be taken about how to use them.
iv)If possible short term insecticides should be used .