Elements replacing hydrogen in a hydrocarbon chain are called heteroatoms. These heteroatoms, including halogens, oxygen, nitrogen, and sulphur, form functional groups in compounds, imparting specific properties regardless of the carbon chain’s length and nature.

Carbon forms bonds not only with hydrogen but also with halogens, oxygen, nitrogen, and sulphur. These elements can replace hydrogen in a hydrocarbon chain, maintaining carbon’s valency.

Carbon’s unparalleled catenation is attributed to its capacity to form strong bonds with other carbon atoms. With a valency of four, carbon can bond with multiple atoms, producing stable compounds with diverse elements due to the strength of its bonds.

Carbon compounds with only single bonds between carbon atoms are termed saturated, while those with double or triple bonds are referred to as unsaturated. The nature of bonding influences the properties of these compounds.

Carbon’s ability to form bonds with other carbon atoms, known as catenation, enables the formation of long chains, branched structures, or rings in carbon compounds. This property contributes to the vast diversity of carbon compounds.

Covalently bonded molecules have strong intramolecular bonds but weak intermolecular forces, resulting in low melting and boiling points. Since no charged particles are formed, these compounds are generally poor conductors of electricity.

Methane (CH₄) is formed by carbon sharing its four valence electrons with four hydrogen atoms, forming covalent bonds. The molecule lacks charged particles, contributing to its low melting and boiling points.

The electron dot structure of NH₃ shows that each hydrogen atom shares electrons with nitrogen, forming single covalent bonds and allowing all four atoms to attain stable noble gas configurations.

Carbon compounds have weak intermolecular forces, reflected in low melting and boiling points compared to ionic compounds. Their poor conductivity is attributed to the absence of ions in their bonding.

With four electrons in its outer shell, carbon aims to achieve noble gas configuration. However, gaining or losing four electrons is impractical due to the difficulty in holding or removing electrons, leading to the absence of ions in carbon compounds.