Work out the shape of an SF6 molecule

To work out the shape of the SF6 molecule we can use a simple equation which allows us to work out the number of electron pairs. The equation is (old group + electrons donated +/- charge) / 2. If the charge is positive then take it away and if it is negative then add it on. So for SF6, the molecule is in group 6, each Fluorine atom donates one electron so 6 electrons donated in total, there is no charge so nothing to add or take away. So the number of electron pairs is (6 + 6 + 0) / 2 = 6 electron pairs. There are no double bonds or lone pairs to worry about so the shape is based on an octahedron, so the observed shape of the molecule is octahedral. All the angles in the molecule are 90 degrees.