GROUP 7

Question 1

appearance of the halogens pure form

Answer 1

fluorine - pale yellow gas
chlorine - green gas
bromine - dark red liquid
iodine - grey solid

Question 2

appearance of the halogens in water

Answer 2

fluorine - reacts with water
chlorine - green solution
bromine - orange solution
iodine - brown solution

Question 3

electronegativity of group 7

Answer 3

decreases down the group
more shielding
weaker attraction between nucleus and bonding electrons

Question 4

boiling points down group 7

Answer 4

increases down the group
larger molecules
more electrons
stronger VDW forces between molecules

Question 5

test for halide ions

Answer 5

silver halides are insoluble
1. add nitric acid to remove unwanted ions
2. add silver nitrate
3. test solubility of precipitate

Question 6

colour of precipitates of halides

Answer 6

chloride - white
bromide - cream
iodide - yellow

Question 7

solubility of halide precipitates in dilute ammonia

Answer 7

chloride - ppt dissolves
bromide - insoluble
iodide - insoluble

Question 8

solubility of halide precipitates in concentrated ammonia

Answer 8

chloride - ppt dissolves
bromide - ppt dissolves
iodide - insoluble