| A | B |
|---|
| chemical symbol | letter(s) representing the name of an element |
| nucleus | contains protons and neutrons |
| atomic number | number of protons in nucleus |
| mass number | number of protons and neutrons in nucleus |
| electrons | travel around outside of nucleus |
| isotope | atom with different number of neutrons |
| deuterium and tritium | isotopes of hydrogen |
| quarks | protons and neutrons are made of this |
| tevatron | caused fast-moving protons to break up |
| energy levels | only contain a maximum number of electrons |
| dot diagrams | represent the outer electrons |
| groups or families | vertical columns of periodic table |
| periods | horizontal rows of periodic table |
| noble gases (group 18) | very stable because outer energy level has 8 electrons |
| halogens | group 17 (example: chlorine) |
| transition elements | groups 3 - 12 (example: cobalt) |
