This free online atomic element lookup instantly gives you the atomic number, atomic mass, category, period, and group for any of the 118 known chemical elements. Search by element name, chemical symbol, or atomic number.
How to Use the Atomic Element Lookup
Type an element's full name (e.g. "Iron"), chemical symbol (e.g. "Fe"), or atomic number (e.g. "26") into the search field.
Click "Search" to see the element's atomic number, atomic mass, category, period, and group.
If nothing is found, double-check the spelling or try the symbol or atomic number instead.
Frequently Asked Questions
All 118 currently known chemical elements, from Hydrogen (atomic number 1) to Oganesson (atomic number 118).
Atomic mass (or standard atomic weight) is the average mass of an element's atoms, measured in atomic mass units (u). For very heavy, unstable synthetic elements, the mass number of the most stable known isotope is shown instead.
Period is the element's row in the periodic table (1-7), and group is its column (1-18). Lanthanides and actinides are shown with no group number, since they sit outside the standard 18-column layout.
Yes, it's completely free, works instantly in your browser, and requires no sign-up.