Chemistry · Chemical Bonding · NEET
VSEPR stands for Valence Shell Electron Pair Repulsion. The idea is very simple: the electron pairs in the outer shell of the central atom all carry negative charge, so they push away from each other. To get as far apart as possible, they arrange in a fixed pattern. That pattern decides the shape of the molecule. So VSEPR is just electrons trying to avoid each other.
Step 1: Find the central atom (usually the least electronegative, and written first, like C in CH4). Step 2: Count how many atoms are bonded to it (bond pairs). Step 3: Count the lone pairs left on the central atom = (valence electrons of central atom - electrons used in bonds) / 2. Step 4: Add bond pairs + lone pairs to get total electron pairs. Step 5: Match the total to the arrangement (2=linear, 3=trigonal, 4=tetrahedral, 5=trigonal bipyramidal, 6=octahedral). Step 6: Remove the lone pair positions to see the final shape. For NEET, this 6-step method solves almost every shape question.
Geometry counts ALL electron pairs (bond pairs + lone pairs). Shape counts only the ATOMS you can actually see. Example: H2O has 4 electron pairs, so its geometry is tetrahedral. But it has 2 lone pairs that are invisible, so the shape you see is bent (V-shaped). Lone pairs decide geometry but they are not part of the visible shape. NEET loves this trap, so always read whether the question asks geometry or shape.
A lone pair belongs to only one atom, so it stays fat and close to the central atom. A bond pair is shared between two atoms, so it is pulled thinner and further away. Because lone pairs take more space, the repulsion order is: lone pair-lone pair > lone pair-bond pair > bond pair-bond pair. This is why lone pairs push bonded atoms closer and change both the shape and the bond angle. This exact order was asked in NEET 2016.
This is a shorthand for VSEPR. A is the central atom, B is a bonded atom (each B = one bond pair), and E is a lone pair on the central atom. So AB3E means 3 bond pairs and 1 lone pair, like NH3 (trigonal pyramidal). AB2E3 means 2 bond pairs and 3 lone pairs, like XeF2 (linear). Learn to write the AB-E code first, and the shape follows automatically.
Use: lone pairs = (valence electrons of central atom - number of single bonds it makes) / 2. Add 1 electron for each negative charge and subtract 1 for each positive charge. Example ClF3: Cl has 7 valence electrons, makes 3 bonds, so (7-3)/2 = 2 lone pairs. That gives AB3E2, which is T-shaped. This shortcut was directly tested in NEET 2018 and NEET 2026.
Consider the molecules CH4, NH3 and H2O. Which of the given statements is false?
Predict the correct order of repulsion between electron pairs as per VSEPR theory.
Match the compound with its shape. A. NH3; B. BrF5; C. XeF4; D. SF6. Shapes: I. Trigonal pyramidal; II. Square planar; III. Octahedral; IV. Square pyramidal.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
VSEPR works very well for main-group molecules with one clear central atom, which covers almost all NEET questions. It can fail for some transition metal complexes and molecules with strong electron delocalisation, but you will not be tested on those exceptions in the shape questions.
No. For VSEPR shape, a double or triple bond counts as ONE electron region (one bond pair location), not two or three. For example CO2 has two double bonds but only 2 regions, so it is linear. This is a very common mistake.
They are linked but not the same. VSEPR predicts the shape by counting electron pairs. Hybridisation (sp, sp2, sp3, sp3d, sp3d2) is the orbital explanation for the same arrangement. Total electron pairs of 2, 3, 4, 5, 6 match sp, sp2, sp3, sp3d, sp3d2. So once you count pairs, you get both the shape and the hybridisation.
Chemical Bonding gives 2 to 3 questions almost every year, and VSEPR shape is one of the most repeated topics (asked in 2016, 2018, 2019, 2021, 2024, 2025 and 2026). Learning this one counting method lets you answer many shape and hybridisation questions quickly without memorising each molecule.
