Chemistry Unit 6

Dipole moment

An IMF in a polar molecule where the positive and negative end separate from eachother. (H2O)

Dipole-Dipole Attractions

When two molecules interact and each one has a dipole moment

Between two polar molecules

Hydrogen Bonds

When an H atom is attached to an N/O/F

Dipole-induced dipole

When one molecule causes a dipole in another molecule

Between one polar molecule and one nonpolar molecule

LDFs

Between everything

bigger molecules - more LDFs

Strength of IMFs from least to most

LDFs → Dipole-induced Dipole → ion-induced dipole → Dipole-Dipole→Hydrogen bond → Ion-Dipole

how are IMFs related to evaporation

high IMFs → harder to evaporate → low vapor pressure

low IMFs → easier to evaporate → high vapor pressure

Electron Geometry

Related to the number of electron domains surrounding the central atoms including lone pairs + bond lines

Molecular Geometry

Only cares about the atoms around the molecules. Changes based on the lone pairs but not counted in the shape.

2 electron domains

no lone pairs

linear

180º

NP

3 electron domains

no lone pairs

trigonal planar 120º NP

4 electron domains

no lone pairs

tetrahedral

109.5º

NP

5 electron domains

no lone pairs

trigonal bipyramidal

90º, 120º

NP

6 electron domain

no lone pairs

octahedral

90º

NP

3 electron domains

1 lone pair

Bent

117.5º

P

4 electron domains

1 lone pair

Trigonal pyramid

107º

P

5 electron domains

1 lone pair

See-saw

90º, 120º

P

6 electron domains

1 lone pair

Square-pyramid

90º

P

4 electron domains

2 lone pairs

bent

104.5

P

5 electron domains

2 lone pairs

T-shaped

90º

P

6 electron domains

2 lone pairs

square-planar

90º

NP

5 electron domains

3 lone pairs

Linear

180º

NP

Octet Rule Exceptions

Be- 4e

Al/B- 6e

P/Xe- 10e

S- 12e