Question

Why the expansion of octet occurs in some elements?

Answer 1

Dear student,

We know elements have 8 electrons in their valence shell. This is called the octet. At times, more than 8 electrons can occupy valence electrons. Expanded octet occurs when an atom is able to have more than 8 valence electrons. For example, in SO₃, the sulfur atom forms 6 covalent bonds, hence it has 12 valence electrons. Expansion of octet is possible only from Period 3 elements onwards, due to the presence of low-lying empty d orbitals that can accommodate the extra electrons.