| A | B |
|---|
| atomic mass | average mass of one atom of an element |
| actinide | an element in the second row of the rare earth elements in periodic table; U uranium |
| alkali metal | element in Group 1; highly reactive; 1 valence e-; never found uncombined |
| alkaline earth metals | element in Group 2 of periodic table; 2 valence e-; not uncombined |
| alloy | mixture of two or more metals |
| atom | smallest particle of an element |
| amu (atomic mass unit) | average mass of one atom of an element |
| atomic number | number of protons in nucleus of an atom |
| chemical bond | force that holds two atoms together |
| conductor | substance that transmits heat or electricity easily |
| corrosion | gradual wearing away of a metaldue to chemical rxn |
| diatomic molecule | molecule composed of two identical atoms |
| electron | tiny, negatively charged particle that moves around the nucleus of atom in energy levels |
| family | elements in the same vertical column of periodic table; group |
| group | elements in sme verticle column of periodic table; family |
| halogen family | elements in Group 17 of periodic table; most active non-metal; 7 valence e- |
| lanthanide | element in first row of rare earth elements in periodic table |
| ductile | metal that can be stretched out into a thin wire |
| malleable | metal that can be hammered into thin sheets |
| nonmetal | elements that are right of zig/zag; dull, brittle;poor conductors |
| metalloid | element that some characteristics of metals & nonmetals; border zig/zag line |
| neutron | small particle in nucleus of atom with no electrical charge |
| noble gas | element in Group 18; have filled valence e-; stable: do not gain, lose, share e- |
| nucleus | central core of an atom containing protons and neutrons |
| Period | horizontal row of elements in periodic table |
| Periodic Table | chart of elements showing the repeating pattern of their properties |
| proton | small, positively charged particle in nucleus of atom |
| reactivity | ease and speed with which elements combine with other elements |
| transition metal | elementd in Groups 3 thru Group 12 of periodic table |
| valence electron | one of the electrons farthest away from the nucleus of the atom; involved in chemical reaction |
