Intermolecular Forces

Question 1

What are Van Der Waals

Answer 1

The attraction between instantaneous and induced dipoles on neighbouring molecules

Question 2

What are permanent Dipole-Dipole attractions

Answer 2

The attraction between the positive end ð+ of the permanent dipole on a molecule with the negative end ð- of the permanent dipole of a neighbouring molecule

Question 3

The strength of Van Der Waals…

Answer 3

Increases as the number of electrons in the molecule increases and explains the trend in melting and boiling points within a homologous series of organic compounds

Question 4

Hydrogen Bonding

Answer 4

The attraction between a lone pair of electrons on a VERY electronegative atom in one molecule and a hydrogen atom in a neighbouring molecule in which the hydrogen atom is covalently bonded to a VERY electronegative atom

Question 5

Two criteria for Hydrogen Bonding

Answer 5

• Hydrogen involved must be directly bonded to a strongly electronegative atom such ass N, O or F (-OH, -NH or HF)

• Atom with which the hydrogen bonds in the second molecule must have one or more lone pairs (unbonded pairs) of electrons

Question 6

Order of strength if Intermolecular Forces of attraction

Answer 6

Strongest: Hydrogen Bonding
Permanent Dipoles
Temporary and Induced