Symmetry element

In particular, a symmetry element can be a mirror plane, an axis of rotation (either proper and improper), or a center of inversion.

The set containing these operations form one of the symmetry groups of the object.

In a molecule that also has an axis of symmetry, a mirror plane that includes the axis is called a vertical mirror plane and is labeled σv , while one perpendicular to the axis is called a horizontal mirror plane and is labeled σh .

[4] The Cn notation is also used for the related, more abstract, cyclic group.

[2] The order in which the rotation and reflection are performed does not matter (that is, these operations commute).