Is the number of total atoms on the left side of a balanced equation always equal to the number of total atoms on the right side of the equation?

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change?

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

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!