Grade -8 (Science ) : Metal and Non -Metals

                   Unit : 13  Metal 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)

i)Alkali metal :The elements of IA group in modern periodic table are called alkali metal , because they are dissolve in water to form metal hydroxide or alkali .

These metals are called very reactive metals because they have only one electrons to their valence so loss one electron very quickly to complete their valence shell .They are also called lightest metal .For example  :Na (Sodium), K (potassium ) etc.

ii)Earth alkaline metals :The elements of IIA group in modern periodic table are called earth alkaline metals, because they are found in the form of oxide on the surface of earth and react with water to produce alkali .For example : Mg (magnesium ) Ca (calcium ).

Transition elements : The elements of groups from IB to VIIB and VIII are called transition elements. They have variable valency. These elements are also called d-block of elements  .

 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.

i)Chalcogens :The elements of VIA group in modern periodic table are called chalcogens ,because these elements are found combined with copper in nature .For example :O (oxygen), S (Sulphur )  etc .

ii)Halogens: The elements of VIIA group in modern periodic table is called  halogen ,because they react with hydrogen to from acid from which simple salt also can be produced I.e. halogen =salt producer .

This group of elements  are also called very reactive non metal because they have 7 electrons to their valence so they receive 1 electron very to complete their valence .

For example : F (Fluorine) ,Cl (chlorine ) etc.

iii)Noble gas or inert gas :The elements of 0 group in modern periodic table are called Noble gas .because they have already 8 electrons to their valence shell so they neither receive nor donate electrons to complete their valence shell .For example :He (Helium), Ne (Neon) ,Ar (Argon ) etc.

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.

Ores : The minerals from which metals can be extracted in large amount are  called ores.

Metallurgy :  The process by which the metals can be extracted from the ores is called metallurgy

Some useful Metals ,Non- Metals and Metalloids

1. 1.)Iron

Symbol =Fe (Ferrum)

Ores :

i)Haematite  : it is also called major ores of iron .

ii)Magnetite

iii)Iron carbonate

iv)Siderite

v)Limonite

vi)Iron pyrite 

Physical properties :

i)It is shiny and grayish white metal .

ii)It is malleable and ductile .

iii)It is good conductor of heat and electricity

Uses :

i)It is used for making different types of pipes rods ,and cable wires .

ii)It is used for making different types instruments and weapons .

iii)It is used for making building ,bridges ,and means of transportation i.e. bus, trucks etc.

iv) It is used for making different types of household utensils .

v) It is used for making steels .

2. 2.) Aluminium

Symbol =Al (Aluminium)

Ores :

i)Bauxite  :It is also called major ores of aluminium.

ii)Felspar

iii)Cryolite

Physical properties :

i)It is shiny and silvery white metal .

ii)It is malleable and ductile .

iii)It is good conductor of heat and electricity

Uses :

i)It is used for making aluminium paint .

ii)It is used for making electric cable .

iii)It is used for making coins .

iv)Due to its malleable ,ductile and light properties it is used for making aeroplane .ship,car etc .

v)It is used for making household utensil  .

 3.)Copper

Symbol =Cu (Cuprum)

Ores :

i)Copper pyrite or chalcopyrite: it is also called major ore of copper .

ii)Chalcocite or copper glance

iii)Cuprite (Ruby copper )

iv)Malachite

v)Azurite

Physical properties :

i)It is shiny and reddish brown metal .

ii)It is malleable and ductile .

iii)It is good conductor of heat and electricity.

Uses:

i)It is used for making cables ,and electric appliances .

ii)It is used for making coins ,and brass .

iii)It is used for making household utensil.

iv)It is also used for making insecticide and pesticides .

4.)Silver

Symbol =Ag (Argentum)

Ores :

i)Argentite or silver glance: It is also called major ore of silver .

ii)Silver copper glance

iii)Horn silver

Physical properties :

i)It is shiny white metal .

ii)It is malleable and ductile .

iii)It is good conductor of heat and electricity.

Uses:

It is used for making valuable household utensil .

ii)It is used for making coins and jewelry .

iii)it is used for making negative in photography .

iv)It is used for silver plating .

5.)Gold

Symbol =Au (Aurum)

Ores :Gold is mostly found free state in nature due to less reactive nature ,so it is also called noble gas, but some important ores of gold are :

i)Alluvial soil

ii)CalaveritePhysical properties:

i)It is shiny yellow metal .

ii)It is malleable and ductile .

iii)It is good conductor of heat and electricity.

Uses of gold :

i)It is used for making jewelry and coins .

ii)It is used for making medals .

iii)It is used for making status.

iv) It is used for gold plating .

6.)Silicon

Symbol=Si

Ores:It is found in form of silica i.e. Sand, Qurtz etc

i.It is brown in colour .

ii.It is poor conductor of heat and electricity .

iii.It is semi metal.

Uses of Silicon :

i.It is used for making glass ,sand paper.

ii.It is used for making solar cell, transistors and computers clips .

iii.It is used for making silicon steel, alloys .

iv.It is used for making ceramics, glue .

7.Sulpher

Symbol:-S

Ores : It is found in free state in volcanic region and combined state in the form of sulphide and sulphate of metal ,large amount in onion, garlic, fish .

Physical properties :

i.It is bright and light yellow in colour.

ii.It is testless and odourless .

iii.It is insoluble in water .

Uses of Sulphur

i.It is used to make medicine i.e.skin ointment and fungicides .

ii.It is used to manufacture matches gun powder .

iii.It is used in manufacture of rubber and dye .

iv.It is used for making sulphuric acid .