Match the element with its number of valence electrons. (4 points) 1. Fluorine a 2. Helium 3. Sodium 4. Aluminum a. 2 b. 3 c. 7 d. 1

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!