Electron Groups

Part of the Structure and Bonding section of Coddy's Chemistry journey. Lesson 16 of 49.

Around a central atom, every electron group repels the others and they spread as far apart as possible. This idea is called VSEPR (valence shell electron pair repulsion).

An electron group is one bond of any kind (single, double or triple) or one lone pair.

Carbon dioxide with two double bonds around carbon, boron trifluoride with three single bonds around boron, and water with two bonds and two lone pairs around oxygen

Count the groups around the central atom: a bond of any kind is one, a lone pair is one

With no lone pairs: 2 groups make a linear molecule, 3 a trigonal planar one, 4 a tetrahedral one.

Challenge

Silane, SiH₄, is a gas used to make computer chips. Its silicon atom is bonded to four hydrogen atoms and has no lone pairs. What shape is the molecule?

Try it yourself

Shape viewerDescribe the molecule SiH₄

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Structure and Bonding

2Covalent Bonds

Sharing Electrons Counting Valence Electrons Drawing Lewis Structures Double and Triple Bonds Lone Pairs Formal Charge Lewis Structures of Ions Recap - Molecule Builder

5Forces Between Molecules

London Forces Dipole-Dipole Forces Hydrogen Bonds Boiling Points Like Dissolves Like Recap - Boiling Contest

8Practice Problems

Recap - Polar Bonds Survey Recap - Pigments and Hexane Recap - Butanol and Ether Recap - Dots on an Oxide

3Shapes of Molecules

Electron GroupsLinear and Trigonal Planar Tetrahedral Molecules Pyramids and Bent Molecules Bond Angles Recap - Shape Detective

6Metals and Giant Structures

Metallic Bonding Diamond and Graphite Giant Covalent Structures Four Kinds of Substance Recap - Material Match