Molecular Geometry Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Molecular Geometry.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

The three-dimensional arrangement of atoms in a molecule, predicted by Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that electron pairs around a central atom arrange themselves as far apart as possible to minimize repulsion, determining the molecule's shape (e.g., linear, trigonal planar, tetrahedral, bent).

Electron pairs repel each other, pushing atoms as far apart as possible — this determines the molecule's shape.

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How to Use These Examples

Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Molecular Geometry starts by identifying valence electrons, likely charges or sharing, and the structure that follows.

Common stuck point: Students often know a formula related to molecular geometry but skip the recognition step: Am I explaining a substance by electron behavior, bond type, molecular shape, polarity, or attractions between particles? That leads to a correct-looking substitution attached to the wrong chemical model.

Sense of Study hint: Ask: Am I explaining a substance by electron behavior, bond type, molecular shape, polarity, or attractions between particles?

Worked Examples

Example 1

medium

What are the electron geometry, molecular geometry, and ideal bond angles for

CH_4

Electron geometry, molecular geometry, and bond angles for CH₄?

Answer

\text{tetrahedral; tetrahedral; }109.5^\circ

First step

C has 4 bonds, no lone pairs.

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Example 2

medium

For

SO_3

, predict the geometry and bond angle.

Geometry and bond angle of SO₃?

Example 3

hard

Predict the geometry of

XeOF_4

(Xe has 5 bonds and 1 lone pair).

Example 4

challenge

Compare the bond angles in

H_2O

(104.5°),

H_2S

(~92°), and

H_2Te

(~90°). Explain the trend.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy

What molecular geometry does a molecule with 2 bonding regions and no lone pairs on the central atom have?

Example 2

easy

What is the ideal bond angle in a tetrahedral molecule like

CH_4

What is the ideal bond angle in CH₄?

Example 3

easy

How many electron domains surround the central atom in a trigonal planar molecule?

Example 4

easy

Does water

H_2O

have a linear or bent molecular geometry?

H₂O: bent or linear?

Example 5

easy

What is the ideal bond angle in a linear molecule?

Example 6

easy

How many bonding regions does a tetrahedral molecule (no lone pairs) have?

Example 7

easy

Ammonia

NH_3

has 3 bonds and 1 lone pair. Is its molecular shape trigonal planar or trigonal pyramidal?

Is NH₃ trigonal planar or trigonal pyramidal?

Example 8

easy

How many electron domains give an octahedral electron geometry?

Example 9

medium

Determine the molecular geometry of

CO_2

(C has 2 double bonds, no lone pairs).

Molecular geometry of CO₂?

Example 10

medium

Predict the molecular geometry of

SO_2

(S has 2 bonds and 1 lone pair).

Molecular geometry of SO₂?

Example 11

medium

What is the molecular geometry of

PCl_5

(5 bonds, no lone pairs)?

Molecular geometry of PCl₅?

Example 12

medium

Why is the H-O-H angle in water (104.5 degrees) less than the ideal tetrahedral 109.5 degrees?

Example 13

medium

Determine the molecular geometry of

BF_3

(3 bonds, no lone pairs on B).

Molecular geometry of BF₃?

Example 14

medium

The ion

NH_4^+

has 4 bonds and no lone pairs on N. What is its geometry and bond angle?

Geometry and bond angle of NH₄⁺?

Example 15

medium

Predict the shape of

XeF_2

(Xe has 2 bonds and 3 lone pairs).

Molecular shape of XeF₂?

Example 16

medium

What is the molecular geometry of

H_2S

(S has 2 bonds and 2 lone pairs)?

Molecular geometry of H₂S?

Example 17

medium

Distinguish electron geometry from molecular geometry for

NH_3

Example 18

challenge

Predict the molecular geometry of

SF_4

(S has 4 bonds and 1 lone pair).

Example 19

challenge

Determine the geometry of

XeF_4

(Xe has 4 bonds and 2 lone pairs).

Example 20

challenge

Compare the bond angles in

CH_4

NH_3

, and

H_2O

and explain the trend.

CH₄ has the largest bond angle; lone pairs compress angles in NH₃ and H₂O

Example 21

easy

What does the acronym VSEPR stand for?

Example 22

easy

How many electron domains does a central atom in a linear molecule (no lone pairs) have?

Example 23

easy

What is the ideal bond angle for trigonal planar geometry?

Ideal bond angle for trigonal planar geometry?

Example 24

easy

How many bonding regions does a central atom in a trigonal pyramidal molecule have, and how many lone pairs?

Example 25

easy

Does the molecular geometry include lone pairs in its name?

Example 26

easy

What is the molecular geometry of

BeCl_2

(Be has 2 bonds, no lone pairs)?

Molecular geometry of BeCl₂?

Example 27

medium

Predict the molecular geometry of

CCl_4

Molecular geometry of CCl₄?

Example 28

medium

Predict the molecular geometry of

H_3O^+

Molecular geometry of H₃O⁺?

Example 29

medium

What is the molecular geometry of

OF_2

(O has 2 bonds, 2 lone pairs)?

Molecular geometry of OF₂?

Example 30

medium

What is the molecular geometry of the

NO_2^-

ion (N has 2 bonding regions and 1 lone pair)?

Molecular geometry of NO₂⁻?

Example 31

medium

Which is more polar overall,

CO_2

H_2O

, and why?

H₂O is polar because its bent shape prevents dipole cancellation

Example 32

medium

Predict the molecular geometry of the

CO_3^{2-}

ion.

Molecular geometry of CO₃²⁻?

Example 33

medium

What is the molecular geometry of

PH_3

Molecular geometry of PH₃?

Example 34

medium

Predict the molecular geometry of

ClF_3

(Cl has 3 bonds and 2 lone pairs).

Example 35

medium

Predict the molecular geometry of

I_3^-

Example 36

medium

Why is

CO_2

nonpolar but

SO_2

polar?

Example 37

medium

How many domains does

SF_6

have on the central atom, and what is its molecular geometry?

Molecular geometry of SF₆ with 6 electron domains?

Example 38

hard

Predict the molecular geometry of

BrF_5

Example 39

hard

H_2O

, which lone pair-bond pair vs bond pair-bond pair repulsion is stronger?

Example 40

hard

Explain why lone pairs in a trigonal bipyramidal geometry occupy equatorial rather than axial positions.

Example 41

hard

Why is the F-S-F bond angle in

SF_4

(seesaw) less than the ideal trigonal bipyramidal angles?

Example 42

hard

CH_2Cl_2

has a tetrahedral electron geometry. Is the molecule polar?

Is CH₂Cl₂ polar? Its tetrahedral geometry with two different substituents creates a net dipole.

Example 43

challenge

NH_3

has bond angle ~107° and

NF_3

has ~102°. Both are trigonal pyramidal — explain the difference.

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Related Concepts

Lewis Structure Covalent Bond Molecular Polarity Polar Covalent Bond

Background Knowledge

These ideas may be useful before you work through the harder examples.

lewis structurecovalent bond