MOLECULAR SHAPES What is the shape of this

MOLECULAR SHAPES

What is the shape of this gerber daisy? Looks two-dimensional but in reality it is three-dimensional.

A Molecule of Methane Electron Dot Structure (Lewis Structure) What is the shape of a molecule of methane? Methane is also three-dimensional. Structural Formula Molecular Shape

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. H H

Linear Diatomic molecules are always linear. Cl Cl H Cl

Linear Be. F 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°.

What things are around nitrogen? A pair of unshared electrons Bonding electrons

. . Electrons repel each other. . . BENT O N F

BENT One unshared pair

BENT Two unshared pair . . Water O . . H H

BENT Water The bond angle in water is 104. 4°.

NH 3 TRIGONAL-PYRAMIDAL

TRIGONAL-PYRAMIDAL One unshared pair