Which element is the most similar to calcium ca

What is the percent by mass of oxygen in fe2o3

In which block of the periodic table is uranium (u) found? s blockd blockp blockf block

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!