Page 80 - CITS - Fitter - Trade Theory

FITTER - CITS

• Metals are sonorous. It means when we strike them, they make a ringing sound.

• Metals are hard. It means they cannot be cut easily.
2 Chemical Property
Metals are chemically reactive with different chemicals.
As- corrosion of metal, oxide layer(rust).

Some of the chemical properties of metals are given below.
• Reaction with Oxygen – Metals react with oxygen and form metallic oxides which are basic in nature.
Metal + Oxygen Metal oxide
Metal oxide + water Base

Example –Magnesium is metal and when it reacts with oxygen, it forms magnesium oxide. When we dissolve
magnesium oxide in water, it gives magnesium hydroxide. The reactions are given below.
2Mg + O2 2MgO

MgO + H2O Mg(OH)2
• An aqueous solution of metal oxide turns red litmus paper into blue.
• Reaction with water - Metals react with water. When a metal reacts with water, metal hydroxide and hydrogen
gas are formed.
Metal + Water Metal hydroxide + hydrogen
Example – Sodium metal reacts with water and forms sodium hydroxide and hydrogen gas. The reaction is
given below –
Na + H2O NaOH + H2
• Reaction with Acid - Metals react with acids and form salt and hydrogen gas. Some metals vigorously react
with acids.

Metal + Acid Metal salt + hydrogen
Example – Magnesium metal reacts with hydrochloric acid and forms magnesium chloride and hydrogen. The
reaction is given below –

Mg + 2HCl MgCl2 + H2
• Reaction with Base - Metals react with bases such as sodium hydroxide and form salt and hydrogen gas.
Metal + Base Metal salt + hydrogen

Example – Aluminium metal reacts with Sodium hydroxide and forms sodium aluminate and hydrogen gas.
The reaction is given below –
Al + NaOH NaAlO2 + H2

• Displacement Reaction - A more reactive metal displaces a less reactive metal from its salt solution. These
types of reactions are called displacement reactions.
Example – Iron is more reactive than copper. So, it displaces copper from its salt. The reaction is given below –

CuSO4 + Fe FeSO4 + Cu
3 Mechanical property
a Malleability:
Metals can convert into thin sheet due to these properties.
As- Gold

65

CITS : CG & M - Fitter - Lesson 11 CITS : CG & M - Fitter - Lesson 11