Question

(a) What is meant by 'allotropes'? Name the various allotropes of carbon.
(b) Why does carbon form largest number of compounds?
(c) Why are some of these called saturated and other unsaturated compounds?
(d) Which of these two is more reactive? Give reason for your answer.
(e) Write the names of the following compounds:

Answer 1

(a) Allotropes are the different physical forms of the same element. Carbon has three different allotropic forms diamond (C₄), graphite (C₃) and Buckminsterfullerene (C₆₀).

(b) Carbon forms the largest number of compounds because of its two properties -

1. Catenation − This is the property of carbon atoms to form bonds with other carbon atoms.
2. Tetravalency − A carbon atom forms four covalent bonds. Moreover, it can form stable single, double and triple bonds with a lot of elements.

(c) Molecules having a single bond are known as a saturated hydrocarbons, for example - alkanes.
Molecules having a double or triple bond are known as an unsaturated hydrocarbon, for example - alkenes and alkynes.

(d) Unsaturated hydrocarbons are more reactive than saturated hydrocarbons. Unsaturated hydrocarbons have double or triple bonds which are weaker compared to the single bonds of saturated hydrocarbons. These double and triple bonds act as reactive sites where addition reactions can occur easily.

(e)
(i) 1-Bromoethane

(ii) Hex-1-yne