| A | B |
|---|
| atomic number | indicates # of protons in the nucleus of an atom |
| electron | a negatively-charged subatomic particle |
| electron configuration | the arrangement of electron by sublevels according to increasing energy |
| energy level | fixed-energy orbit that electrons occupy as they circle the nucleus |
| energy sublevel | an electron energy results from splitting of a main energy level |
| isotopes | atoms having the same atomic # but different mass# |
| mass number | indicates the # of protons & neutrons in the nucleus of an atom |
| neutron | a neutral subatomic particle with approx mass of one amu |
| orbital | a region about the nucleus of an atom with a high probability of finding an electron with a given energy |
| proton | a positively-charged subatomic particle with approx mass of one amu |
| quantum mechanical atom | model describing electron energy in terms of its location about the nucleus |
| atomic mass | average mass of all naturally occuring isotopes of an element |
| atomic mass unit (amu) | unit of mass equal to 1/12 the mass of a c-12 atom |
| atomic nucleus | center of an atom containing protons and neutrons |
