Final answer:
Carbon forms four covalent bonds instead of two because one 2s electron gets promoted to a 2p orbital, leading to sp³ hybridization which allows for four equivalent orbitals to form stable bonds, contributing to carbon's stability in compounds with four covalent bonds.
Step-by-step explanation:
Despite having a 2s²2p² valence electron configuration that suggests carbon might form just two bonds due to its pair of unpaired 2p electrons, carbon indeed typically creates compounds with four covalent bonds. This occurs because one of the 2s electrons undergoes promotion to an empty 2p orbital, leading to a sp³ hybridization. This hybridization results in four equivalent orbital shapes suitable for forming stable bonds, as seen in methane (CH4).
The energy released during the formation of four bonds makes the compounds more stable compared to those with only two bonds, even though forming these extra bonds initially requires extra energy to promote an electron from 2s to 2p. Carbon's ability to form multiple stable covalent bonds is also demonstrated in compounds like carbon dioxide (O=C=O), where it forms two double bonds, firmly establishing its tetravalency.