| A | B |
|---|
| atom | smallest part of an element that has the properties of that element |
| nucleus | the central core of the atom containing the protons and neutrons |
| proton | positively charged particle in the nucleus of the atom |
| neutron | located in the nucleus of the atom; it has no charge. |
| electron | negatively charged particle that moves around the nucleus of the atom. |
| isotope | two or more atoms of the same element with the same number of protons but different numbers of neutrons. |
| atomic number | the number of protons in the nucleus of the atom |
| atomic mass | the number of protons plus neutrons in the atom of an element. |
| energy levels | the possible energies that the electrons of an atom can have |
| electron cloud | a visual model of the most likely locations for the electrons in an atom |
