TY2C10
1. fluorine: gas, yellow
chlorine: gas, yellow/green
iodine: liquid, dark red/brown
bromine: shiny grey black solid which sublimates to violet vapour.

2. a. sublimation is where a substance transitions from a solid directly to a gas

   b. A violet vapour is observed.

3. a. Electronegativity is the ability of an atom to attract a pair of electrons in
a covalent bond.

   b. Electronegativity is higher in fluorine because fluorine has less electrons
and therefore less shielding and a smaller atomic radius.

4. The halogens are poisonous or toxic so should
5. Iodine has a higher boiling point than bromine because the van der waals
forces are greater between iodine molecules than bromine molecules. This is
because larger molecules with more electrons have greater induced dipole
diploe forces and hence greater van der waals forces. This means more energy
is required to break these bonds. As iodine has more electrons and is larger
then bromine these forces and hence the boiling point is greater.

ACTIVITY P229

1. There are 1/(10^5) kg of iodine in 1kg of the heated seaweed.
There are m/M_r = (1000*0.0001)/253.8 = 0.0004 moles of iodine in the batch.

2. 2I- (aq) -> I2 (aq) + 2e-, 2H+ (aq) + H202 (aq) + 2e- -> 2H2O (l)

3. The oxidation state of I- ions is -1 and the oxidation of the I2 which are
formed is 0 hence the increase in oxidation state shows oxidation.

4. yellow/brown ???

5. Iodine dissolves in the cyclohexane causing the purple colour as it is more
soluble in organic solvents.

6.Iodine crystals, grey-black

7. Purple vapour is produced as the iodine sublimates.

TY1C10

1. Intermolecular forces between methane molecules? Van der waals forces, they arise due to assymetries in the electron cloud of a molecule.
2. a) Butane b) CH_3CH(CH_3)CH_3

T1C14

1.