Chemistry - Molecular shapes and intermolecular bonding

What does VESPR stand for ?

valence-shell-electron-pair repulsion theory

What is the VESPR theory based on ?

The fact that electron pairs in the valence shell repel each other

What are a bond pair of electrons ?

When two electrons are shared between atoms

What are a lone pair of electrons ?

When two electrons aren’t shared and aren’t involved in a bond

What are the different shapes of molecules ?

Linear

Trigonal planar

Tetrahedral

Pyramidal

V-shaped/bent

What is it if a molecule has non-polar covalent bonds only ?

The molecule is also non-polar

What is it if a molecule has polar covalent bonds ?

It may be polar or non-polar

What characteristics must a polar molecule have ?

It must contain polar covalent bonds

The centres of positive and negative charge must not coincide (the molecule must not be symmetrical)

What characteristics must a non-polar molecule have ?

It contains only non-polar bonds

It contains polar covalent bonds but the centres of negative and positive charge coincide (the molecule is symmetrical)

What are molecules containing polar covalent bonds that are linear, trigonal planar or tetrahedral ?

Non-polar (as long as the atoms surrounding the central atom are all the same)

What are molecules containing polar covalent bonds that are pyramidal or V-shaped ?

Polar

What are three types of intermolecular forces ?

Permanent dipole-dipole forces (including hydrogen bonding)

London dispersion forces

Ion-dipole forces

What are permanent dipole-dipole forces ?

The force of attraction between the slightly positive charged end of one molecule and the slightly negatively charged end of a neighbouring molecule

Hydrogen bonds

A specific type of permanent dipole-dipole attraction between a hydrogen atom of one molecule and a small, highly electronegative atom (nitrogen, oxygen or fluorine) of a neighbouring molecule

What are London dispersion forces ?

Weak, temporary forces of attraction between neighbouring molecules as a result of temporary dipoles (caused by the movement of electrons within a molecule)

Why are London dispersion forces weaker than permanent dipole-dipole forces ?

Because they are temporary

What are ion-dipole forces ?

Forces of attraction between an ion and a molecule with a dipole