| A | B |
|---|
| atomic mass | average mass of one atom of an element |
| periodic table | chart of elements based upon their properties |
| nucleus | central core of an atom |
| proton | positively charged nuclear particle |
| neutron | nuclear particle with no charge |
| electron | negatively charged part of an atom |
| atomic mass unit (amu) | mass of proton or neutron |
| atomic number | number of protons in an atom |
| chemical symbol | letter(s) for element |
| group | column on the periodic table |
| family | column on the periodic table |
| period | horizontal row on periodic table |
| valence electron | electrons involved in a chemical reaction |
| malleable | material that can be hammered into shape |
| ductile | material that can be pulled into a wire |
| conductor | transmits heat or electricity well |
| magnetic | attracted to a magnet |
| reactivity | ease and speed that an elements combines with others |
| corrosion | gradual wearing away of a metal |
| alloy | mixture of two or more metals |
| alkali metal | Group 1 element |
| alkaline earth metal | Group 2 element |
| transition metal | element in Groups 3 to 12 |
| lanthanide | element in first period of rare earths |
| actinide | element in second period of rare earths |
| nonmetal | lacks most of the characteristics of a metal |
| noble gas | Group 18 element |
| diatomic molecule | two atoms of same element |
| halogen | Group 17 element |
| metalloid | some characteristics of both metals and nonmetals |
| semiconductor | conducts electricity under certain conditions |
| plasma | state of matter with no electrons |
| nuclear fusion | small nuclei form large nuclei |
| supernova | explosion of a massive star |
