2.6 Shapes of molecules & intermolecular forces (Spec)

Question 1

Electron-pair repulsion theory

Answer 1

Electrons repel as far apart as possible

Lone pairs repel more strongly than bonded pairs as closer to nucleus

Question 2

Electronegativity

Answer 2

Tendency of an atom to attract a shared pair of electrons in a covalent bond

Question 3

Non-polar bond criteria

Answer 3

Identical atoms
OR
Low difference in electronegativity

Question 4

Polar bond criteria

Answer 4

High difference in electronegativity

Question 5

Overall dipole criteria

Answer 5

Asymmetrical molecule
OR
Unequal dipole strength in opposite directions

Question 6

Trigonal planar bond angle

Answer 6

120 degrees

Question 7

Tetrahedral bond angle

Answer 7

109.5 degrees

Question 8

Linear bond angle

Answer 8

180 degrees

Question 9

Pyramidal bond angle

Answer 9

107 degrees

Question 10

Non-linear bond angle

Answer 10

104.5 degrees

Question 11

Octahedral bond angle

Answer 11

90 degrees

Question 12

Hydrogen bond criteria and explanation

Answer 12

N-H OR O-H OR F-H bonds on two different molecules
Lone pairs -> electron density -> partial negative charge -> electrostatically attracted to partial positive on H of another molecule involved in one of mentioned bonds
Strongest intermolecular force

Question 13

London forces

Answer 13

Instantaneous dipole as electrons orbit atom in orbitals
Partial negative charge repels electrons in nearby molecules, inducing dipole
Opposite partial charges electrostatically attract
Weakest intermolecular force

Question 14

Permanent dipole - dipole interactions

Answer 14

Permanent dipole - permanent dipole
Opposite partial charges on dipoles electrostatically attract
Second-strongest intermolecular force
Permanent dipole - Induced dipole
Permanent dipole partial negative repels electrons in nearby non-polar molecule, induces dipole
Opposite partial charges on dipoles electrostatically attract
Third-strongest intermolecular force