Amongst the following, the total number of species NOT having eight electrons around central atom in its outermost shell, is
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Quick Answer
Option D
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— The octet rule states that atoms tend to combine in such a way that each atom has eight electrons in its valence shell,…Step-by-step solution
1AnswerD·
The octet rule states that atoms tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. However, there are exceptions to this rule.
- NH₃ (Ammonia): Nitrogen is the central atom. It has 5 valence electrons. It forms 3 single bonds with hydrogen atoms and has 1 lone pair. Total electrons around N = (3 × 2) + 2 = 8 electrons. It obeys the octet rule.
- AlCl₃ (Aluminium chloride): Aluminium is the central atom. It has 3 valence electrons. It forms 3 single bonds with chlorine atoms. Total electrons around Al = 3 × 2 = 6 electrons. It does NOT obey the octet rule (electron deficient).
- BeCl₂ (Beryllium chloride): Beryllium is the central atom. It has 2 valence electrons. It forms 2 single bonds with chlorine atoms. Total electrons around Be = 2 × 2 = 4 electrons. It does NOT obey the octet rule (electron deficient).
- CCl₄ (Carbon tetrachloride): Carbon is the central atom. It has 4 valence electrons. It forms 4 single bonds with chlorine atoms. Total electrons around C = 4 × 2 = 8 electrons. It obeys the octet rule.
- PCl₅ (Phosphorus pentachloride): Phosphorus is the central atom. It has 5 valence electrons. It forms 5 single bonds with chlorine atoms. Total electrons around P = 5 × 2 = 10 electrons. It does NOT obey the octet rule (expanded octet).
The species not having eight electrons around the central atom are AlCl₃, BeCl₂, and PCl₅. There are 3 such species.
Correct Answer: (D)
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