Atomic number is the number of protons in an atom's nucleus. It defines the element: every atom with 6 protons is carbon, with 8 protons is oxygen, and so on.
Periodic Table
Explore all 118 elements by group, period, block and chemical family
The structure reveals chemical patterns, not just a list of symbols
The periodic table arranges elements by atomic number and recurring electron-configuration patterns. Columns indicate groups with similar properties; rows indicate periods; the s, p, d and f blocks show the dominant orbital region. The view above focuses on fast lookup: search, chemical family, group, period, block and reference atomic weight.
Search, filter and inspect elements quickly
- Use search to find an element by symbol, name, atomic number or approximate mass.
- Filter by chemical family to isolate noble gases, transition metals, lanthanides, actinides and other groups.
- Select an element to see atomic weight, group, period, block and classification in the side panel.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
- IUPAC Periodic Table of ElementsIUPAC — Official reference for names, symbols, groups and standard atomic weights.
- CIAAW Standard Atomic WeightsCIAAW / IUPAC — Standard atomic weights table and isotopic intervals used as reference.
- PubChem Periodic TableNIH / PubChem — Interactive table and element data used for visual and educational validation.