How to predict bond angles?

[Peter Dis1G]

Can anyone give some examples? Thanks a lot~

[An Dang 3F]

If there are no lone pairs on the molecule, then the molecular shape will be same as the electron arrangement. When lone pairs are present, the molecular shape of the molecule will be different from the electron arrangement. For example, h20 has four places of electron concentration, so the electron arrangement is tetrahedral, but it has two lone pairs so the molecular shape will be bent with a bond angle of fewer than 180 degrees. For CO2, it has two places of electron concentration with no lone pairs, so the electron arrangement and molecular shape will be linear with a bond angle of 180 degrees.

[SitharaMenon2B]

Bond angles are based on the shape and lone pairs of a molecule. For example, all molecules with AX4 (4 atoms bonded to the central atom) will be tetrahedral and will have bond angles of 109.5. When there are lone pairs, the angles are decreased, but the exact angle is specific to the molecule. Two molecules that are AX3E would both be trigonal pyramidal and have angles less than 109.5, but the exact angles would be different.

[Peter Dis1G]

Cool,appreciate it!!