Periodic Table of the Elements

Elements are arranged by atomic number in rows called periods and columns called groups. There are 7 periods and 18 groups. Elements in the same group tend to share chemical behavior. For example, the group 1 metals all react vigorously with water.

Each color marks an element category, such as alkali metal, noble gas, or lanthanide. Click any color in the legend to highlight just that category, and click it again to clear the filter.

Type a name, symbol, or atomic number in the search box - for example 'gold', 'Au', or '79'. The table highlights the element, scrolls to it, and opens its details.

The atomic number is the count of protons in the nucleus, and it defines the element. The atomic mass is the weighted average mass of the element's atoms, measured in atomic mass units.

They belong in periods 6 and 7, but showing all 30 of them inline would make the table impractically wide. The two detached rows are the f-block. The placeholders marked 57-71 and 89-103 show where each row connects to the main table.

A bracketed mass means the element has no stable form in nature. The number shown is the mass number of its most stable known isotope instead of a standard atomic weight.

An electron configuration describes where an element's electrons live. Iron's [Ar] 3d⁶ 4s² means: take argon's full electron shells, then add six electrons in the 3d subshell and two in the 4s subshell. The bracket is noble-gas shorthand that keeps long configurations readable.

No. The whole table, search, and filters run in your browser. Nothing you type or click is sent to a server or stored.