 If a molecule has four electron groups around the central atom, as does CH4, it has a tetrahedral geometry with bond angles of 109.5°.

• A tetrahedron is a geometric shape with four triangular faces.
• CH4 is shown here with both a ball-and-stick model (left) and a space-filling model (right). Space-filling models more closely portray molecules, yet ball-and-stick models are often used to clearly illustrate molecular geometries.