Periodic Table A table of chemical elements arranged in order of atomic number.

Pure Substance A pure substance cannot be separated into simpler substances by chemical or physical means

Element An element is a pure substance that cannot be separated into simpler substances by chemical or physical means.

Groups Groups are vertical columns on the periodic table.

Periods Periods are horizontal rows on the periodic table.

Chemical Symbol Abbreviations for the chemical elements Ex. Ca is the chemical symbol for calcium