Question

(a) Define non-metals. Give five examples of non-metals.
(b) Name a non-metal which conducts electricity.
(c) Name a non-metal having lustre (shining surface).
(d) Name a non-metal which is extremely hard.
(e) How do non-metals react with oxygen? Explain with an example. Give equation of the reaction involved. What is the nature of the product formed? How will you demonstrate it?

Answer 1

(a) Non-metals are elements that do not show metallic characteristics, such as conductivity of electricity and heat, malleability and ductility.They are non-lustrous, generally soft and non-sonorous. Hydrogen, nitrogen, oxygen, carbon and silicon are five examples of non-metals.

(b) Carbon in the form of graphite is a non-metal that conducts electricity.

(c) Iodine is a non-metal that is lustrous (shining surface).

(d) Carbon in the form of diamond is a non-metal, which is extremely hard.

(e) Non-metals react with oxygen to form acidic or neutral oxides. The oxide is covalent in nature as it is formed by the sharing of electrons.When carbon burns in air (oxygen), it forms an acidic oxide called carbon dioxide.

For example, the non-metal, carbon reacts with oxygen:
C(s) + O₂(g) $\to$CO₂(g)

The product formed is acidic in nature. It can be demonstrated by dissolving carbon dioxide in water to form carbonic acid. This resultant solution or carbonic acid, when added to blue litmus solution, changes the solution's colour to red. This shows that the oxide formed is acidic in nature.