CBSE Class 10 Answered

The octet rule states that atoms tend to gain, lose or share electrons so as to have eight electrons in their outer electron shell.

Limitations of octet rule:

•  Formation of duplets

Formation of hydrogen molecule (having 2 electrons in valence shell)

• Elements of group 1, 2 and 13 form covalent compounds in spite of its valence shell containing less than 8 electrons.
• The elements of groups 15, 16 and 17 have more than four electrons in their valence (outermost) shell and are seen to form stable compounds in which there are more than eight electrons around the central atom.
• Formation of radicals (odd electron) also violate octet rule