Hybridization — Prelims Strategy

Prelims Strategy

To effectively tackle NEET questions on hybridization, a systematic approach is essential. The primary strategy revolves around the steric number (SN) method.

1
Identify the Central Atom: — This is usually the least electronegative atom or the unique atom in the molecule.
2
Count Valence Electrons: — Determine the number of valence electrons of the central atom. For ions, add electrons for negative charge and subtract for positive charge.
3
Count Sigma Bonds: — Count only sigma bonds. For single bonds, it's 1 sigma. For double bonds, it's 1 sigma and 1 pi. For triple bonds, it's 1 sigma and 2 pi. Remember, only sigma bonds contribute to the steric number.
4
Calculate Lone Pairs: — Subtract the electrons used in sigma bonding from the total valence electrons (adjusted for charge), then divide by 2 to get the number of lone pairs.
5
Calculate Steric Number (SN): — SN = (Number of sigma bonds) + (Number of lone pairs).
6
Determine Hybridization:

* SN = 2 $implies$ $sp$ * SN = 3 $implies$ $sp^2$ * SN = 4 $implies$ $sp^3$ * SN = 5 $implies$ $sp^3d$ * SN = 6 $implies$ $sp^3d^2$ * SN = 7 $implies$ $sp^3d^3$

Tips for Numerical/Conceptual Problems:

Practice with VSEPR: — Hybridization and VSEPR theory are inseparable. Once hybridization is determined, use VSEPR to predict the precise molecular geometry and bond angles, especially when lone pairs are present. Remember LP-LP > LP-BP > BP-BP repulsion order.
Organic Molecules: — For carbon atoms in organic compounds, assume no lone pairs unless explicitly stated or implied. The hybridization is simply determined by the number of sigma bonds (4 for $sp^3$, 3 for $sp^2$, 2 for $sp$).
Exceptions/Special Cases: — Be aware of molecules like $PCl_5$ (trigonal bipyramidal, $sp^3d$) where axial and equatorial bonds differ, and lone pairs prefer equatorial positions.
Trap Options: — Distractors often involve confusing hybridization with molecular geometry (e.g., $H_2O$ is bent, but $sp^3$ hybridized) or miscounting sigma/pi bonds. Always be meticulous in counting.
S-character: — Remember that higher s-character leads to increased electronegativity, shorter bond length, and greater bond strength. This is a common conceptual question.