| Description of Term | Term | Woo! |
| Atoms with the same number of protons (i.e. same atomic number) but a different number of neutrons. | |
| A positively charged particle of mass 1.6726x10-27 | |
| A tenet of quantum mechanics that says that the position and momentum of any particle cannot both be known precisely at the same time. | |
| The small, dense central region of an atom around which electrons orbit. Made up of protons and neutrons. | |
| An ion with a net positive charge. | |
| An uncharged atomic particle of mass 1.67493x10-27 . It resides in the nucleus. | |
| Description for two elemental species with the same electronic configuration | |
| A set of electron orbitals with the same principal and second quantum numbers. | |
| Any atom or molecule with a net charge. | |
| Associated with one particular atom, in which electrons reside | |
| German for 'building up', a systematic procedure for determining the electron configuration of any atom | |
| A set of electron orbitals with the same principal quantum number. | |
| The highest energy shell in an atom, containing valence electrons. All interactions between atoms take place through the electrons of the valence shell. | |