| A | B |
|---|
| Atom | smallest particle of an element that maintains the properties of that element |
| Atomic mass | average mass of one atom of an element (from particles in the nucleus) |
| Atomic number | the number of protons in the nucleus of an atom; used to determine an element's position in the Periodic Table |
| Electrical charge | a property of a subatomic particle; positive (protons), negative, (electrons), or neutral (neutrons) |
| Electron | a negatively charged particle in the electron cloud surrounding the atomic nucleus |
| Electron cloud | the negatively charged space containing electrons that surrounds the atomic nucleus |
| Neutron | a (neutral) particle with no electrical charge within the atomic nucleus |
| Nucleus | the positively charged center of an atom containing the protons and neutrons |
| Periodic Table | a conceptual model in which the elements are organized according to their properties; often displayed as a chart |
| Proton | a positively charged particle within the atomic nucleus; used to identify an element |
| Subatomic particle | a particle smaller than an atom, such as a proton, neutron, or electron |
| Valence electron(s | electron(s) located in outer energy level (electron shell) |
