MCQ Detailed View

Valency is defined as the combining capacity of an atom, determined by the number of electrons it can share, gain, or lose to achieve a stable electronic configuration. Carbon has an atomic number of 6, with an electronic configuration of 1s² 2s² 2p². This means carbon has four electrons in its outermost shell (second shell) and needs four more electrons to complete its octet.

Carbon achieves stability by sharing its four valence electrons with other atoms through covalent bonds. This ability to form four covalent bonds makes carbon tetravalent. It can bond with hydrogen, oxygen, nitrogen, sulfur, halogens, and even with other carbon atoms to form long chains and complex structures. This tetravalency is the foundation of organic chemistry, allowing carbon to form millions of stable compounds.

Examples of tetravalency are found in simple molecules like methane (CH₄), where one carbon atom shares its four electrons with four hydrogen atoms. In ethane (C₂H₆), carbon atoms bond with each other and hydrogen atoms using all four available bonds. Similarly, in carbon dioxide (CO₂), carbon forms two double bonds with oxygen atoms, again utilizing its four valence electrons.

Other options such as divalent (2), trivalent (3), or univalent (1) do not apply to carbon under normal conditions because carbon always uses four bonds in its stable compounds. Some exceptions occur in certain ions or excited states, but in classical organic chemistry, carbon is universally tetravalent.

Understanding carbon's valency is crucial because it explains the vast variety of organic compounds and their ability to form chains, rings, and complex macromolecules that are the basis of life.