Unit 3 - The atom and chemical substances

- Atomic nucleus: its formed by protons electrons( protons, electrons ) and neutrons, and it's in the middle of the atom outside of the atom( middle of the atom, outside of the atom ), occupying a very small big( small, big ) space relative to the rest of the atom.
- Rest of the atom Out part Helmet( Rest of the atom, Out part, Helmet ): also called the shell. Electrons Protons Neutrons( Electrons, Protons, Neutrons ) occupy the empty space around each atomic nucleus. Scientists thought electrons orbited surrounded jumped( orbited, surrounded, jumped ) the nucleus.