They differ in the number of protons in their nucleus.
Not normally.
unreactive
They are 'inert' elements, and gases too.
None of them would react :) ♥ ♥ ♥
Argon.
noble gases
helium, neon, argon, krypton, xenon and radon
neon
Helium, neon, and argon are the three lightest members of the noble gases.
Helium, Neon, Argon, Krypton, Xenon, and Radon.helium (studyisland answer)
helium neon argon krypton xenon radon
The first four are (in order of increasing number / mass: He = Helium, Ne = Neon, Ar = Argon, Kr = Krypton Xe = Xenon and Ra = Radon are the other two noble gases
Noble gases
Elements
They are all gases.
Column 18.
Not normally.