# Transcript

Here are five of the six noble gases: helium, neon, argon, krypton and xeon. They're all colourless and transparent. Krypton and xeon form compounds only with difficulty. Helium, neon and argon don't form compounds at all.

As we descend the group in the periodic table the atomic number and relative atomic mass increases. The gasses get denser.

Helium - helium is lighter than air. Neon is just lighter. Argon and krypton - I've just got to unstick these from the anchorage... Argon and krypton are both heavier than air. And xeon, xeon is the heaviest of the lot, you've heard of a lead balloon, well this is it.