alleryStart learning →Why is hydrogen an exception to the octet rule?
AIt never forms any covalent bonds
BIt always loses its single electron
CIt needs ten electrons to fill up
DIt needs only two electrons to fill up
Answer & Solution
Correct answer: D. It needs only two electrons to fill up
1. Hydrogen's valence shell is the first shell, which holds a maximum of two electrons.
2. So hydrogen is full at two electrons and has no way to reach eight.
3. It therefore forms one covalent bond and stops, which is why it sits outside the octet rule.
4. The transition and inner transition elements are also outside the rule, for different reasons.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 7 "Chemical Bonding and Molecular Geometry", section The Octet Rule_
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