Group 7

what is gypsum used as

a building plaster material

describe colours of diatomic molecules + states

fluorine- pale yellow gas

chlorine- green gas

bromine- red brown liquid

iodine- grey/black solid

why is the F-F bond weak?

• small size of fluorine atom leads to repulsion between electrons as they are close together

what happens to size of atom down group

• increases

• greater atomic number + electron

• more shielding + inner shell repulsion

Melting point + why

increases down group, larger atoms has more electrons + stronger VDW forces between molecules

describe volatility when bp is low

the more volataile

halogens are

oxidising agents

oxidising ability of halogens … down group

decreases

what happens during a displacement reaction

a more reactive halogen displaces a less reactive halogen

ions that do not partake in a reaction are

spectator ions

the ionic compound starting material is always

colourless (except for transition metals)

Describe why this displacement reaction happens?

Cl2 + 2NaBr → Br2 + 2NaCl

chlorine is a stronger oxidising agent than bromine so able to oxidise bromide ions into bromine ions

ions are … than atoms

larger