4.2 Group 7

Question 1

what are group 7 elements called

Answer 1

halogens

Question 2

what are halogens

Answer 2

group 7
covalently bonded
simple molecular substances

Question 3

trend in properties

Answer 3

all diatomic
get darker down the group
MP/BP increases down the group
less reactive down the group

Question 4

why do they get less reactive down the group

Answer 4

they all need to gain an electron
but further down the group:
atoms have more electron shells
the extra electron is further away from the nucleus
so its attraction to the nucleus is weaker

Question 5

test for chlorine

Answer 5

damp blue litmus paper turns white

this is because the chlorine acts as a bleaching agent so removes the colour from the paper

Question 6

displacement reactions

Answer 6

more reactive halogens displace less reactive halogens from their compounds

Question 7

redox reactions

Answer 7

halogen displacement reactions are all redox reactions
this is because one thing gains an electron (reduced) and another loses an electron (oxidised)
The more reactive halogen steals an electron from the halide ion in the salt

Question 8

Fluorine appearance

Answer 8

Very pale yellow colour
Gas

Question 9

Chlorine appearance

Answer 9

Pale green colour
Gas

Question 10

Bromine appearance

Answer 10

Brown
Liquid

Question 11

Iodine appearance

Answer 11

Dark grey
Solid

Question 12

Astatine appearance

Answer 12

Black
Solid