Periodic Table of Elements
REFElement Categories
Alkali Metals
Alkaline Earth
Transition Metals
Post-Transition
Metalloids
Nonmetals
Halogens
Noble Gases
Lanthanides
Actinides
Understanding the Periodic Table
Elements are arranged by atomic number (number of protons). Rows are periods, columns are groups with similar properties. Metals on left, nonmetals on right, metalloids in between. Element categories shown by color. Click any element to view detailed information including atomic mass, electron configuration, and state at standard temperature and pressure.