What is the mass of a mole of lithium oxide?

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!

Which samples do the atoms have the least kinetic energy

Why is any chemical reaction always balanced? give reasons and explain the easiest way to solve the balancing problems in chemical equations with stoichiometric coefficients upto 20 as hit and trial doesn't always work. give full reasoning