Halogens
Science: KS3, topic 2.4.9
The Halogens
The halogens are found in group 7 of the periodic table. They can be commonly found in disinfectants and bleach.
Halogens
- The halogens are found in Group 7.
- They are a very dangerous set of elements.
- If you breathe in the toxic gases they could cause death.
- They can also cause burns on the skin that need to be treated at hospital.
- The non-metals in group 7 include (from top of the group to the bottom of the group).
- Fluorine (F).
- Chlorine (Cl).
- Bromine (Br).
- Iodine (I).
- Astatine (At).
Properties
- The colour of the halogens gets darker as you go down the group.
- At room temperature, they have all three states of matter within the group. The elements have decreasing energy as you go down the group.
- Fluorine and chlorine are gases.
- Bromine is a liquid.
- Iodine and astatine are solids.
- The density trend of the halogens is that they increase as you go down the group.
Reactivity
- A more reactive halogen will ‘displace’ a less reactive halogen from their salt.
- The halogens become less reactive as you go down the group.
- This is because the electron to be gained from another element is further from the nucleus.
Test yourself on Halogens
The Halogens
Why do halogens become less reactive as you go down the group?