⚛️ Periodic Table Reference

Search by element symbol, name or atomic number (1-36: Hydrogen through Krypton) to see its key facts.

Element (symbol, name or number)

What the lookup covers

The table holds the first 36 elements, hydrogen through krypton, and returns five facts for each: symbol, name, atomic number, standard atomic mass in unified mass units, and category. Typing Fe, iron or 26 all reach the same entry.

Matching is exact but case-insensitive. fe works, iro does not - there is no partial search or suggestion list.
Names follow IUPAC spelling, so element 13 is Aluminium and aluminum finds nothing. Search 13 instead.
Categories used are alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, nonmetal, halogen and noble gas.

Turning atomic mass into molar mass

The mass shown in u is numerically the same as grams per mole, which is what makes it useful in the lab:

H2O  = 2 x 1.008 + 15.999 = 18.015 g/mol
NaCl = 22.990 + 35.45     = 58.44  g/mol

Add one line per element in the formula and multiply by its subscript. A hydrate needs its water counted separately: copper(II) sulfate pentahydrate, CuSO4·5H2O, is 63.546 + 32.06 + 4 x 15.999 + 5 x 18.015, or 249.68 g/mol.

These are standard atomic weights - averages over the isotopes found on Earth, which is why chlorine is 35.45 rather than a whole number. Use them for molar mass, never for the mass of a single named isotope.

Frequently asked questions

What is the atomic mass of iron?

55.845 u, with atomic number 26. That means 26 protons, and a mole of iron weighs 55.845 grams.

Why is argon heavier than potassium?

Argon is 39.948 u at number 18 and potassium 39.098 u at 19, so mass drops as the atomic number rises. The table is ordered by proton count, not weight, and argon's common isotopes simply carry more neutrons. It is one of three such inversions in the full table.

Why does searching for element 92 return nothing?

The reference stops at 36, krypton. Everything from rubidium onward, uranium included, is outside the range, and the tool says so rather than guessing.