The Periodic Table of Poetry

Beryllium

Atomic element number 4
is highly reactive like the element before.
There are many uses for this rare metal,
but not making pots, or cans, or kettles.
Beryllium is good if you're making a rocket.
You might think that's all, but I'm not done yet.
Beryllium is also used in airplanes.
There's so many uses for its alloys that it's insane.