Which one of the following molecules contains an incomplete octet of the central atom?
- SF6
- AICI3
- CH4
- PF5
- H2O
The Correct Option is B
Solution and Explanation
The octet rule states that atoms in molecules tend to have eight electrons in their valence shell, like the noble gases. However, some molecules do not follow this rule.
SF\(_6\): Sulfur has more than eight electrons in its valence shell, as it is able to accommodate more than eight electrons due to the availability of d-orbitals.
AlCl\(_3\): Aluminum in AlCl\(_3\) only has six electrons in its valence shell, which is an example of an incomplete octet, meaning it does not satisfy the octet rule.
CH\(_4\): Carbon in CH\(_4\) follows the octet rule as it shares four electrons with four hydrogen atoms, completing its octet.
PF\(_5\): Phosphorus in PF\(_5\) has ten electrons in its valence shell, which is allowed as phosphorus can expand its octet.
H\(_2\)O: Oxygen in H\(_2\)O has eight electrons in its valence shell, fulfilling the octet rule.
Thus, the molecule AlCl\(_3\) contains an incomplete octet of the central atom.
The correct option is (B) : \(AlCI_3\)
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