Structure 2

Question 1

Valence Shell Electron Pair Repulsion (VSEPR model)

Answer 1

theory is based on notion that because electron pairs in the same shell carry the same charge, they repel each other and so spread themselves as far apart as possible.

• single, double, triple, or non-bonding electron domains
• shape of molecule is determined by angles between bonded atoms
• non-bonding pairs have higher concentration of charge because they aren’t bonded which causes slightly more repulsion
• multiple bonds also have a slightly concentrated charge and more repulsion because they contain 2 or 3 pairs of electrons

non bonding > multiple bond > single bond

Question 2

Volatility

Answer 2

Molecule with stronger intermolecular forces is less likely to vaporize - tendence of an object to vaporize

Question 3

Solubility

Answer 3

non polar in non polar
polar in polar
solubility of polar compounds is reduced in large compounds since only a small part of it will be polar
giant molecular substances are usually insoluble in all solvents

Question 4

Electrical conductivity

Answer 4

covalent compounds can not conduct because they don’t have ions
polar covalent molecules can not conduct, but their molten states or solutions can

Question 5

sigma bond

Answer 5

formed by the head on combination of atomic orbitals where the electron density is concentrated along the bond axis

Question 6

pi bond

Answer 6

formed by lateral combination of p-orbitals where the electron density is concentrated on opposite sides of the bond axis.

weaker than sigma bonds because their electron density is further from the positive charge of the nucleus.

Question 7

addition polymerisation

Answer 7

when double bonds of monomer molecules break and make new covalent bonds with neighbouring molecules to form a chain.

Question 8

condensation polymerisation

Answer 8

two functional groups react to form a new covalent bond, with the release of a small molecule

small molecule can be H2O, NH3, or HCl