Who Am I?

Allos,

I am a silvery gray metallic who reacts slowly with water. I’m in Group 2 which is in Room 4. I have 20 electrons in total, which I have 2 on the 1st and 4th shell and 8 on shell 2 and 3, I was used as a reducing agent in preparing other metals, like thorium and uranium. One thing to let you know is that I’m also a mineral to help making your bones a lot stronger.

Who am I?

Farewell, my friend, Anonymous Element