unit 1a: shapes of molecules

negatively charged so they repel the electrons in other bonds in a molecule

they try to minimise repulsive forces

valence shell electron pair repulsion

linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral

when both electrons come from the same atom

electrons pairs involved in bonding

these have a greater repulsive effect than bonding pairs so their presence in a molecule causes slightly distorted shapes

subtract the number of atoms around the central atom from the number of electron pairs, any left over must be non-bonding

180°

120°

109.5°

120° and 90°

90°

trigonal pyramidal, 107°

angular, 105°

T-shape, <90° <120°

square planar

seesaw

linear

square pyramidal