Beginner Topic 153 of 1102 Bonding & Molecular Structure
Linear Geometry
Two electron groups arranged at 180 degrees, as in CO2 and BeCl2.
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In-depth explanation of Linear Geometry
Linear geometry arises when a central atom has two electron domains, which place themselves 180 degrees apart to minimize repulsion. The central atom is typically sp hybridized, and its two hybrid orbitals point in opposite directions. A linear molecule with two identical terminal atoms is nonpolar because its bond dipoles cancel. Linear geometry can also arise for species with five electron domains, two bonds and three lone pairs, as in XeF2, where the lone pairs occupy the equatorial positions. It is among the simplest shapes described by VSEPR.
Going deeper: Linear Geometry
Key ideas: Linear applies to AX2 (BeCl2, CO2, HCN) and AX2E3 (XeF2, I3-). Bond angle is 180 degrees. The central atom is sp for two domains and sp3d for five. Diatomic molecules are linear automatically. CO2 has two sp carbon-oxygen sigma bonds and two perpendicular pi bonds.
Common mistakes and connections: Students think all triatomic molecules are linear or all bent ones have two lone pairs, but H2O is bent while CO2 is linear. Another error is saying linear molecules are always nonpolar, when HCN is linear and polar because its ends differ. Connects to sp hybridization, alkynes, polarity and IR vibrations.
Visualization of Linear Geometry
Each carbon in acetylene has two electron domains, so the H-C≡C-H skeleton is perfectly linear with 180 degree bond angles. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Carbon dioxide is linear with two equal C=O bonds, so the molecule is nonpolar.
Frequently asked questions about Linear Geometry
What is Linear Geometry?
Two electron groups arranged at 180 degrees, as in CO2 and BeCl2.
Is Linear Geometry a beginner, intermediate or advanced topic?
Linear Geometry is a beginner topic in Bonding & Molecular Structure. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Linear Geometry?
Study these earlier topics in Bonding & Molecular Structure first: VSEPR Theory, Electron Domain Geometry, Molecular Geometry.
What comes after Linear Geometry?
The next topics in Bonding & Molecular Structure are Trigonal Planar Geometry and Tetrahedral Geometry.
Can I practise Linear Geometry with quizzes?
Yes. The interactive lesson includes a self-check question on Linear Geometry, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Where Linear Geometry fits in Bonding & Molecular Structure
Linear Geometry is topic 38 of 104 in Bonding & Molecular Structure.