Chemistry reference
Periodic Table of the Elements
Select an element to see its key properties. Search by name, symbol, or atomic number.
Tip: select a family to highlight it. Select again to show every element.
How to read the table
Groups are vertical columns. Elements in a group often have similar chemical behavior because they have related valence-electron patterns.
Periods are horizontal rows. Atomic number increases from left to right, one proton at a time.
Atomic mass is the weighted average for naturally occurring isotopes. Bracketed values indicate the mass number of a representative isotope.