The molecular geometry of a molecule refers to the way in which the atoms of a molecule are arranged. This arrangement influences many properties of the molecule.
Table of Molecular Geometries
Molecule type provides a generalized way in which molecules can be expressed.
"A" represents the central atom of the molecule - the one in which all the other are grouped around.
"X" represents atoms that are around the perimeter of the central atom. These atoms do not necessarily all have to be of the same element (or functional group).
"E" represents lone pairs of electrons, which take up about the same amount of space about the central atom as the "X" atoms.