Last time we talked about fluorine, the very most reactive chemical element. Now we add a single proton to the fluorine nucleus and come to Element 10, the LEAST reactive chemical element. What a difference a charge can make!
Actually, neon is quite common in the cosmos but quite rare on earth. It is fifth, after the elements that we have already discussed, because it is mostly a light even/even nucleus. But that is not what makes it outstanding.
There are three stable isotopes of neon, 20Ne, at almost 91% natural abundance on earth, 21Ne, at about a quarter on one per cent, and 22Ne, the remainder. This gets important later.