Understanding Metals and Non - Metals Notes - SSC 2014 Preparation by ednexa.com

1. Understanding Metals and Non - metals
Introduction
We know that elements have been classified into metals, nonmetals
and metalloids. Examples of metals – Copper, gold, silver, iron
Examples of nonmetals – Chlorine
Examples of metalloids – Silicon, Germanium
In day to day life, we can use metals in large scale.
Physical Properties of metals
1.
Metals are solids at room temperature with exception of mercury
and gallium which are in liquid form at room temperature.
2.
Metals have shine (in its pure state) and can be polished to give
highly reflective surface.
3.
Metals have the ability to withstand hammering and can be made
into thin sheets. This property is called as malleability.
4.
Metals have ability to be drawn into thin wires which is called as
ductility.

2. 5.
Metals have good conductors of heat and electricity.
6.
Metals have high melting and boiling points.
7.
Sonorous : The metals that produce a sound on striking a hard
surface are said to be sonorous.
Physical Properties of Nonmetals
1.
Non – metals are either in solid or gaseous state with the exception
of bromine which is in liquid state.
2.
Non – metals usually do not have luster, except iodine and diamond.
3.
There is lack of malleability and ductility.
4.
They are bad conductors of heat and electricity.
5.
They do not possess property of hardness ( except carbon).
Chemical Properties of Metals
I.
Reactions of Metals with oxygen
1.
Metals react with oxygen forming metal oxides.

3. 2.
Generally Metal oxides are insoluble in water, but if dissolved in
water, form alkalis.
3.
Metal oxides are usually basic in nature but some metal oxides such
as aluminium oxide and zinc oxide react both with acids as well as
bases to produce salt and water. Hence they are called as
Amphoteric Oxides.
i.
Aluminum oxide reacts with hydrochloric acid to form
aluminium chloride and water.
Al 2 O 3  6HCl  2AlCl 3  3H 2O

Aluminium
oxide
ii.
Aluminium oxide reacts with sodium hydroxide forming sodium
aluminate and water.
Al 2 O 3  2NaOH  2NaAlO 3  H 2O

Sodium
Aluminate

4. Examples :
i.
Magnesium does not react with oxygen at room temperature
but on heating,
magnesium burns in air with intense light and heat to form
magnesium oxide.

2 Mg  O 2  2 MgO

ii.
Sodium is very reactive :
Sodium reacts with oxygen in air at room temperature forming
sodium oxide.
4 Na  O 2 

2Na 2O
Sodium oxide
Hence, sodium is stored under kerosene oil to prevent its
reaction with oxygen, moisture and carbon dioxide.
Reactions with explanations
1.
Zinc burns in air only on strong heating to form zinc oxide.
heat
2Zn  O 2  2ZnO
zinc
oxide

5. 2.
Iron does not burn even on strong heating, but iron filings burn
vigorously when sprinkled in the flame of the burner.
heat
3Fe  2O 2  Fe 3 O 4
Iron
oxide
3.
Copper is least reactive. It does not burn, but on heating, the hot
metal is coated with a black coloured layer of copper oxide.
heat
2 Cu  O 2  2CuO
Copper
oxide
4.
Aluminium develops a thin oxide layer when exposed to air.
heat
4 Al  3O 2  2 Al 2O 3
Aluminium
oxide
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