The only group where you can find a gas, a liquid, and a solid side by side at room temperature. Tap a shape to match each element to its real state and colour.
GasLiquidSolid
FFluorinePale yellow gas
Atomic number
9
Atomic mass
19.0
The most reactive element on the entire periodic table — it will even react with glass. In tiny, safe amounts it's added to toothpaste and drinking water to protect teeth.
Why so reactive? Halogens have seven electrons in their outer shell — just one short of a full set. Grabbing a single electron from another atom completes that shell, so halogens react eagerly with almost anything that will give one up.
1. Which halogen is the only one that's liquid at room temperature?
2. Which halogen is a solid that gives off a violet vapour?
3. How many electrons does a halogen have in its outer shell?
4. Which halogen reacts so strongly it can even attack glass?
5. Which halogen is the pale yellow-green gas once used to disinfect swimming pools?