Element by Number Lookup

About this calculator

Every chemical element has a unique atomic number — the count of protons in its nucleus — which is what actually defines the element on the periodic table, as codified by IUPAC. This lookup takes that number and returns the element's name, its one- or two-letter symbol, and its standard atomic mass (the weighted average of its naturally occurring isotopes), giving you the same identification you'd get from reading a periodic table cell, just by number instead of by symbol or position.

Chemistry students, teachers preparing worksheets, and anyone working from a dataset or problem set that references elements only by atomic number use it to quickly confirm which element and mass they're dealing with without scanning a full 118-element chart. It's also a handy cross-check when studying periodic trends — since atomic number increases left-to-right and top-to-bottom across the table, the lookup helps connect a raw number to the element's actual position and properties.