Can someone answer these questions..? 1. Describe one sign of a chemical change from the example with the iron nail above

2. Describe an additional sign of a chemical change from the expanse above.

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!