MOLECULAR SHAPES
What is the shape of this gerber daisy? Looks two-dimensional but in reality it is three-dimensional.
Electron Dot Structure (Lewis Structure) Structural Formula Molecular Shape What is the shape of a molecule of methane? Methane is also three-dimensional. A Molecule of Methane
Molecules have three-dimensional shapes. There are many different molecular shapes possible. How can we determine what shape a particular molecule will have?
VSEPR Theory (Valence-Shell Electron-Pair Repulsion) VSEPR theory states that repulsion between the pairs of valence-electrons surrounding an atom causes these electron pairs to be oriented as far apart as possible. HH
Linear Cl H Diatomic molecules are always linear.
Linear BeF 2 No unshared pairs
The bond angle in linear molecules is 180°.
Trigonal-planar BF 3 No unshared pairs
The bond angle in trigonal planar molecules is 120°.
Tetrahedral CH 4 No unshared pairs
The bond angle in tetrahedral molecules is 109.5°.
A pair of unshared electrons What things are around nitrogen? Bonding electrons
O N F.. BENT Electrons repel each other.
BENT One unshared pair
Water O H H.. BENT Two unshared pair
BENT Water The bond angle in water is 104.4°.
NH 3 TRIGONAL-PYRAMIDAL
One unshared pair TRIGONAL-PYRAMIDAL