Element ATC Swap: Beryllium

Henry (while studying chemistry): "Mom, do you know anything about the element Beryllium?"
Me: "Sure. It's element #4 and it's abbreviation is Be. It's the major compound in emeralds."
Henry: "How do you know that?"
Me:  "I'm doing an art swap with friends. 
We're making little cards about each of the elements."
Henry (staring at me; sighs): "Of course you are."