Properties of the halogens

The Halogens are group 7 on the periodic table

The elements in group 7 of the periodic table are referred to as the halogens. But what do you need to know about these elements and the way they behave? Halogen molecules are made of two atoms; halogens at the top of the periodic table are gases and ones at the bottom are solid; halogens produce coloured vapours; and when they react with hydrogen they produce acids. How do you remember this? Read on!

1. Molecular structure

Halogen molecules contain 2 atoms — The halo brigade always consists of one hero and one sidekick. There are always **two**.

**Halogen molecules always have 2 atoms.**

2. States of the Halogens

In the halogen group gasses are at the top and solids at the bottom — They protect the air in the sky above and the solid ground below.

**Gases are at the top of their column of the periodic table, solids are at the bottom.**

3. Coloured vapours

When danger threatens, the halo brigade flies up to deal with it. As they fly, they leave coloured trails behind them.

**Halogens all have coloured vapours.**

4. Displacement

Halogens higher up the table displace ones at a lower position — The more powerful hero angel wants a piece of the action first, so she shoves her less powerful sidekick out of the way. (Displacement)

**Halogens higher up in the table displace the ones that are lower in the table.**

5. React with hydrogen to make acids

When halogens react with hydrogen it makes poisonous acids — The threat is quite often a high dragon (hydrogen). When the two of them fight, the wounded dragon spills poisonous, acid blood.

**Halogens react with hydrogen to make poisonous acids.**

To recap:

A halo brigade always has two members (halogens always have two atoms)
They protect the sky above and solid ground below (they are gases at the top of the periodic table and solids at the bottom)
They leave coloured trails when they fly (they all have coloured vapours)
The hero angel shoves the sidekick angel out of the way (halogens higher on the table displace the ones that are lower on the table)
When the angel fights the dragon, she spills its poisonous, acid blood (Halogens react with hydrogen to make poisonous acids).