4.3 HALOGENS Flashcards
1
Q
how are the elements bonded?
A
- covalently bonded
- simple molecular substances
2
Q
properties of group 7 elements:
A
- all diatomic
- colours get darker down the group
- melting/ boiling point increases down the group
3
Q
colour of fluorine:
A
- F2
- very pale yellow
- gas
4
Q
colour of chlorine:
A
- Cl2
- pale green
- gas
5
Q
colour of bromine:
A
- Br2
- brown
- liquid
- volatile
- releases brown fumes
6
Q
colour of iodine:
A
- I2
- dark grey
- solid
- sublimes
- releases purple fumes
7
Q
colour of astatine:
A
- At2
- black
- solid
8
Q
what do halogens form when they react with metals?
A
ionic compounds
9
Q
what happens to reactivity as you go down the group?
A
get less reactive
10
Q
why do the halogens get less reactive as you move further down the series?
A
- all halogen atoms need to gain an electron to fill their outer shell
- this happens less easily as you go down the group because:
- atoms have more electron shells
- the extra electron is further from the nucleus
- so its attraction to the nucleus is weaker
11
Q
test for chlorine:
A
damp blue litmus paper turns white because chlorine acts as a bleaching agent
12
Q
what do hydrogen and chlorine react to form?
A
hydrogen chloride (colourless)
13
Q
why does the reaction of hydrogen and chlorine produce a colour change?
A
- due to the substances involved
- HCl is a covalently bonded, simple molecular substance
- it is a gas because it has a low boiling point due to weak IMFs
14
Q
what happens when you dissolve HCl into water?
A
- HCl (g) dissolves to form HCl (aq)
- HCl (aq) dissociates to form H+ (aq)
- the H+ (aq) is acidic
- HCl (aq) is called hydrochloric acid
15
Q
what happens when you dissolve HCl into methylbenzene?
A
- HCl (g) dissolves to form HCl (org)
- HCl (org) cannot dissociate
- there is no H+ (org)
- HCl (org) is not acidic
