chemical bonding

Question 1

instantaneous dipole- induced dipole attractions

Answer 1

-( all types of molecules)
at a particular instant, the distribution of electrons may not be even or symmetrical for a non-polar molecule because electrons are in a state of continual motion
- instantaneous dipole induces a dipole in the neighbouring molecules (weakest)

Question 2

why do branched isomers have lower boiling points than straight-chain isomers?

Answer 2

• more spherical in shape, reducing surface area of contact
  -less extensive instantaneous dipole-induced dipole forces of attraction between molecules, which needs less energy to overcome

Question 3

solubility

Answer 3

energy released on forming intermolecular forces of attraction between solute and solvent is sufficient to compensate for the energy required to overcome the solvent-solvent attractions and solute-solute attractions

Question 4

charge density

Answer 4

-higher charge density of cation, cationic radius drops
-larger number of delocalised valence electrons in the mobile electron cloud
-stronger attraction between cations and delocalised electrons
-stronger metallic bond , higher melting point

Question 5

metals- high melting and boiling point

Answer 5

large amount of energy is needed to overcome the strong electrostatic forces of attraction between metal cations and delocalised mobile valence electrons

Question 6

good conductor of electricity (ionic)

Answer 6

good electrical conductors in molten states because there are delocalised mobile valence electrons to carry charges throughout the lattice

Question 7

malleable

Answer 7

layers in the lattice can slide over each other without breaking the strong metallic bonds

Question 8

ionic compounds good conductors of electricity in molten or aqueous state

Answer 8

crystal lattice breaks down into free mobile ions that act as charge carriers, conduct electricity when a potential difference is applied

Question 9

ionic compounds hard brittle

Answer 9

very hard because of strong electrostatic forces of attraction must be partially overcome to deform the crystal
-layers of ions slide such that ions of the same charge meet and repel one another, shattering the crystal

Question 10

covalent character

Answer 10

if cation has high charge density, then the cation has high polarising power, can attract electrons from an ion

Question 11

low melting and boiling points (simple covalent)

Answer 11

energy is used to overcome the weak intermolecular forces of attraction

Question 12

permanent dipole-permanent dipole attraction

Answer 12

polar molecule has permanent dipoles with non-zero dipole moments. H atom directly bonded to F, O or N atom