| A | B |
|---|
| atomic mass | an element's average masses of all the isotopes |
| element | simplest type of pure substance |
| chemical symbol | shorthand way of writing an element |
| chemical formula | chemical symbols together to show a compound |
| atomic number | how many protons in the nucleus of an atom |
| valence electron | electron in the outermost energy level of an atom |
| ion | charged particle formed when an atom gets or loses electrons |
| ionic bond | chemical bond that involves a transfer of electron |
| covalent bond | chemical bond that electrons are shared. |
| subscript | small number to the lower right of a chemical symbol that gives the number of atoms of the element in the compound |
| coefficient | number in front of a symbol or formula to show how many atoms or molecules are in the reaction |
| molecule | combination of atoms formed by a covalent bond |
