Question

Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds.

Answer 1

The atomic number of carbon is 6. This means that it has 4 electrons in its outermost shell and it needs 4 more electrons to attain noble gas electronic configuration. It cannot form C⁴⁺ cation, as the removal of 4 valence electrons requires a huge amount of energy. The cation formed has 6 protons and 2 electrons. This makes it highly unstable. Carbon cannot form C⁴⁻ anion, as its nucleus with 6 protons cannot hold 10 electrons. Thus, carbon achieves noble gas electronic configuration by sharing its 4 electrons with other elements—that is, it forms covalent compounds.