Asap
that last part that’s blank

V1t2 = v2t1 is an expression of who’s law

May someone me with these science questions

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!