Periodic Table Lookup
Search chemical elements by symbol, name or atomic number.
Overview
The Periodic Table Lookup is a searchable directory of all 118 chemical elements. Type a symbol (Fe, Au, Hg), a name (iron, gold, mercury) or an atomic number (26, 79, 80) and the table returns the element's full row of properties: atomic number, symbol, name, atomic mass, period, group, category and electronic configuration.
It is built for chemistry students working through homework, science writers double-checking properties and developers wiring up a chemistry-aware UI. Long-tail queries it covers include "atomic mass of uranium", "electron configuration of carbon", "what element is symbol Hg" and "noble gases in periodic table".
How it works
The dataset is the IUPAC standard table of the elements, with atomic masses given as the most recent published values (some are weighted averages of natural isotopes; some are the mass number of the most stable isotope for synthetic elements). Each row records the symbol, name, atomic number, atomic mass, group (1-18), period (1-7), block (s, p, d, f) and a category tag.
Categories include alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, reactive nonmetal, halogen, noble gas, lanthanide and actinide. Search runs a case-insensitive contains match across symbol, name and atomic number, so "26", "iron", "fe" and "ferr" all return iron.
Examples
H → Hydrogen, 1, 1.008 u, period 1, group 1, reactive nonmetal
Fe → Iron, 26, 55.845 u, period 4, group 8, transition metal
Au → Gold, 79, 196.967 u, period 6, group 11, transition metal
U → Uranium, 92, 238.029 u, period 7, actinide
FAQ
Why is the atomic mass of some elements bracketed?
Bracketed values are the mass number of the most stable isotope rather than a weighted average. Elements without naturally occurring isotopes — most actinides, all transactinides — are reported this way.
What's the difference between group and period?
Group is the column on the periodic table (1-18) and indicates similar chemistry. Period is the row (1-7) and indicates how many electron shells are populated.
Why is hydrogen in group 1 even though it's not a metal?
Hydrogen has one valence electron, which makes its chemistry partly resemble the alkali metals — but it also forms covalent bonds and acts like a nonmetal. Its placement is a compromise; some tables list it both in group 1 and group 17.
Are there elements beyond 118?
None have been confirmed. Element 119 and beyond are predicted theoretically and would need to be synthesised one nucleus at a time, with vanishingly short half-lives.
What does block (s, p, d, f) mean?
The block indicates which subshell receives the last-added electron. Group 1 and 2 are s-block, groups 13-18 are p-block, transition metals are d-block, and the lanthanides and actinides are f-block.