| A | B |
|---|
| nucleus | small, dense positively charged center of atom |
| subatomic particles | particles smaller than an atom (protons, neutrons, electrons) |
| proton | positively charged particle found in the nucleus |
| neutron | subatomic particle with no charge found in the nucleus |
| atomic number | equal to the number of protons |
| isotope | atom with a different number of neutrons |
| atomic mass | equal to the number of protons plus neutrons |
| electron | negatively charged particle found outside nucleus |
| electron cloud | space in which electrons are likely to be found |
| quark | particle that makes up all other known particles in the nucleus |
