| A | B |
|---|
| atomic mass | The average mass of one atom of an element. |
| periodic table | A chart of the elements showing the repeating pattern of their properties. |
| nucleus | The central core of an atom, containing protons and neutrons. |
| proton | A small, positively-charged particle in the nucleus of an atom. |
| neutron | A small particle in the nucleus of an atom that has no electrical charge. |
| electron | A tiny, negatively charged particle that moves around the nucleus of an atom. |
| atomic mass unit | A unit used to measure the mass of particles in an atom. A proton has a mass of 1 amu |
| atomic number | The number of protons in the nucleus of an atom. |
| chemical symbol | A one or two letter representation of an element |
| group | Elements in the same vertical column of the periodic table; also called a family. |
| family | Elements in the same vertical column of the periodic table; also called a group. |
| period | A horizontal row of the Periodic Table of the Elements. |
| valence electron | The electrons in the outermost shell of an atom. |
| malleable | A term used to describe a material that can be hammered flat or rolled into shape. |
| ductile | A term used to describe a material that can be pulled out into a long wire. |
| conductor | A substance that transmits heat or electricity easily. |
| magnetic | A characteristic of metals that are attracted to magnets and can be made into magnets. |
| reactivity | The ease and speed with which an element or compound combines with other elements or compounds. |
| corrosion | The gradual wearing away of an element due to a chemical reaction. |
| alloy | A mixture of two or more metals. |
| alkali metal | An element in Group 1 of the Periodic Table. |
| alkaline earth metal | An element in Group 2 of the Periodic Table. |
| transition metal | An element in Groups 3 through 12 of the Periodic Table. |
| lanthanide | An element in the first row of the rare earth elements in the periodic table. |
| actinide | An element in the second row of the rare earth elements in the periodic table. |
| nonmetal | An element that lacks most of the properties of a metal. |
| salt | A compound formed when a metal and a nonmetal combine. |
| diatomic molecule | A molecule composed of two atoms of the same element. |
| halogen family | The elements in Group 17 of the Periodic Table. |
| noble gas | Elements found in Group 18 of the Periodic Table |
| metalloid | An element that has some of the properties of metals and some of the properties of nonmetals. |
| semiconductor | An element that can conduct electricity under some conditions. |
