Molecular Geometry Calculator
VSEPR shape, hybridisation and bond angle from two counts.
Work out Molecular Geometry. VSEPR shape, hybridisation and bond angle from two counts. Shows the working, not just the answer.
Count attached ATOMS, not bonds. A double bond counts once — which is why CO₂ is linear.
Molecular shape
Bent
Steric number 4 · sp³ · about 104.5°
Electron geometry counts everything around the central atom; molecular geometry describes only where the atoms sit. Water has tetrahedral electron geometry and a bent shape, because the two lone pairs are there but invisible in the molecular structure. Count bonded ATOMS rather than bonding pairs. A double or triple bond occupies one region of space, so carbon dioxide has a steric number of 2 and comes out linear despite having four bonding pairs on the carbon. Lone pairs are fatter than bonding pairs and push harder, which is why the angles come in slightly below the ideal — 109.5° drops to about 107° in ammonia and 104.5° in water as each lone pair is added.
How the Molecular Geometry Calculator works
Enter how many atoms are bonded to the central atom and how many lone pairs it carries. Count atoms rather than bonds — a double bond occupies one region of space, which is why carbon dioxide comes out linear despite having four bonding pairs on the carbon.
Also known as: vsepr calculator · molecular shape calculator · hybridization calculator · bond angle calculator
Frequently asked questions
What is the difference between electron geometry and molecular geometry?
Electron geometry counts everything around the central atom including lone pairs; molecular geometry describes only where the atoms sit. Water is tetrahedral in electron geometry and bent in shape.
How do I count bonding groups?
One per attached atom, regardless of bond order. A double bond counts once because both pairs occupy the same region — which is why CO₂ has a steric number of 2 and is linear.
Why is water's bond angle 104.5° rather than 109.5°?
Because lone pairs take up more space than bonding pairs and push the bonds closer together. Ammonia with one lone pair drops to about 107°, and water with two drops to 104.5°.
How does hybridisation follow from the steric number?
Directly: 2 is sp, 3 is sp², 4 is sp³, 5 is sp³d and 6 is sp³d². The number of hybrid orbitals has to match the number of electron regions being accommodated.
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