inorganic chemistry: Group 7

	state/appearance RTP	characteristics of ←	colour in solution
fluorine
chlorine
bromine
iodine

	state/appearance RTP	characteristics of ←	colour in solution
fluorine	yellow gas	very reactive, poisonous
chlorine	pale yellow/green gas	reactive, poisonous, dense	pale green
bromine	red/brown liquid	dense, volatile	orange
iodine	grey solid	shimmery, crystalline, sublimes into purple vapour	dark brown

what is the structure and bonding of halogens

• simple molecular (strongly covalent bonded molecules, weak intermolecular forces)

• Each molecule contains two halogen atoms joined by a single covalent bond.

colours down the group get _______

colours down the group get DARKER

m/b points ______ down the group and why…

m/b points INCREASE down the group

• the molecules become larger

• the intermolecular forces become stronger

• more energy is needed to overcome these forces

Chlorine, bromine and iodine react with _____ and non-______ to form compounds

metals and non-metals to form compounds

which group are the halogens in

group 7 → 7 electrons in outer shell

reactivity _____ down the group and why

reactivity DECREASES down the group

• halogens have 7 electrons in outer shell, means they have to gain one, have to attract it

• it gets harder to attract the extra electron the further away it is from the nucleus (more shells/larger atomic radius)

the rate of reaction will be _____ down the group

The rate of reaction is slower for halogens which are further down the group

equation, Sodium + chlorine →

Sodium + chlorine → sodium chloride

2Na(s) + Cl₂(g) → 2NaCl(s)

properties of halogens as you go DOWN the group and simple def why (3)

• high boiling/melting points → stronger intermolecular forces

• less reactive → electron to be attracted further away from nucleus bc more shells

  • darker colour

what is a halogen displacement reaction

A halogen displacement reaction: when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide

• more reactive element pushes out less reactive element

rank reactivity of Br2, Cl2 and I2

• Chlorine

• Bromine

• Iodine

reacts with	potassium chlorine solution	potassium bromide solution	potassium iodide solution
chlorine water (green)
bromine water (orange)
iodine water (brown)

the same table but inverted - makes you think

reacts with	chlorine	bromine	iodine
potassium chloride solution
potassium bromide solution
potassium iodide solution

why is fluorine most reactive

Fluorine is the smallest halogen, which means its outermost shell is the closest to the positive nucleus of all the halogen

• Therefore, the ability to attract an electron is strongest in fluorine making it the most reactive

describe halogen displacement reaction in terms of electrons

chlorine + iodine with ions

cl2 + 2I - → 2cl- + I2
electrons are passed from the iodine to the chlorine