(2.5-2.8C) G7- Halogens

What are the elements in group 7 known as?

Halogens

Why do halogens have similar reactions?

They all have 7 electrons in their outermost shell.

How do halogen atoms form molecules?

They are diatomic non-metals, so they form covalent bonds.

Iodine- State the:

formula

appearance at room temperature

colour in solution

I₂

Grey solid (rt)

dark brown solution

Bromine- State the:

formula

appearance at room temperature

colour in solution

Br2

red brown liquid (rt)

orange solution

Chlorine- State the:

formula

appearance at room temperature

colour in solution

Cl2

pale yellow-green gas (rt)

pale green solution

Describe and explain the trend of melting+boiling points as you go down group 7.

m/b points increase → atoms become larger → intermolecular forces increase → more energy required to overcome forces

Describe and explain the trend of reactivity as you go down group 7.

reactivity decreases → number of shells increases → distance between outer shell and nucleus increases → electrostatic attractions are weaker → harder to attract an electron to fill the outer shell and create an ion

What happens to the colours as you descend the group?

They get darker.

Chlorine, bromine and iodine react with ____ + ____ to form ____.

metals + non-metals to form compounds

What are metal halides?

Halogens react with some metals to form ionic compounds which are metal halide salts with a -1 charge.

What are non-metal halides?

simple molecular covalent structures that form when halogens react with non-metals.

What is a halogen displacement reaction?

A reaction in which a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.

Rank the 3 halogens in terms of highest to lowest reactivity.

Chlorine

Bromine

Iodine

What happens to halogen atoms when they react?

They gain an electron to create a full outer shell, resulting in -1 ions.