What you want.. you would need to post your question
They can learn more about Earth's history and environment. Studying rocks can also help scientists discover clues about what Earth was like millions of years ago. That can help them comprehend on our effects on the environment and its probable effects on humans.
Because electrons are the only piece of the atom that is outside of the nucleus. the protons and neutrons are inside the nucleus.
then also the electrons itself have the charge to begin with