The halogens Flashcards
1
Q
in which block are the halogens
A
p-block
2
Q
state and colour of fluorine
A
pale yellow gas
3
Q
state and colour of chlorine
A
green gas
4
Q
state and colour of bromine
A
red-brown liquid
5
Q
state and colour of iodine
A
black solid
6
Q
what factors increase down group 7
A
- nuclear charge
- number of e-
- atomic radius
- boiling point
7
Q
why does the boiling point of the halogens increase down the group
A
- more electrons moving down the group, strength of the temporary dipoles increases.
- Increased dipoles mean greater London forces
8
Q
what type of reactions are halogens often involved in
A
- redox reactions
- they gain 1 e- to form 1- halide ion
9
Q
why does electronegativity decrease down group 7
A
- increase in atomic radii
- shielding outweighs the increase in nuclear charge
- less attraction between nucleus and valent e-
10
Q
why is fluorine the most reactive
A
- atomic radius increases down the group
- greater shielding
- less nuclear attraction to attract an electron from another species
11
Q
what happens when a more reactive and less reactive halogen react
A
- more reactive halogen will displace a less reactive halide ion from solution resulting in a colour change corresponding to the displaced halogen
12
Q
why are halogens less reactive down group 7
A
- decreasing electronegativity reduces halogen’s ability to attract and e- to form 1- ion
13
Q
what can be done to make colour change in displacement reactions easier to see
A
- in a separating funnel, shake the reaction mixture with an organic solvent like hexane
- non-polar halogen dissolves in non-polar organic solvent
- polar halide dissolves in aq layer
- organic layer above aq
14
Q
what colour is chlorine in water
A
pale green
15
Q
what colour is bromine in water
A
orange
