Chemistry - Halogens

What are elements in group 7 called?

Halogens

What do they exist as?

Diatomic molecules

What do they include?

Florine, Chlorine, Bromine, Iodine

What happens when the atomic number increases?

They become darker, they decrease in reactivity, and their boiling points increase

Fluorine (F₂)

Boiling point: -180°C

Appearance at room temperature: Yellow gas

Characteristics: Very reactive, toxic

Chlorine (Cl₂)

Boiling point: -34°C

Appearance at room temperature: Green gas

Characteristics: Fairly reactive, dense, toxic

Bromine (Br₂)

Boiling point: 59°C

Appearance at room temperature: Red-brown liquid

Characteristics: Toxic, high volativity

Iodine (I₂)

Boiling point: 185°C

Appearance at room temperature: Black solid

Characteristics: Gives off purple vapour

What do halogens form when reacting with metals?

Halide salts which are ionic compounds. During these reactions, a halogen atom will gain an electron and become a negative ion

What is needed for a halogen displacement reaction to happen?

The ‘ine’ halogen has to be the most reactive. If the ‘ide’ halogen is more reactive, it won’t happen.

Why is it that the higher up the group you go, the more reactive the element is?

Because there are less shells so less distance between the outer electrons and the nucleus so stronger electrostatic forces of attraction so the one electron is stolen more easily