Lithium

01 / A closer look

Meet Lithium

Lithium has atomic number 3: every atom of this element contains 3 protons. It belongs to period 2, group 1 of the periodic table.

In a neutral atom, the number of electrons equals the number of protons. Isotopes of this element share the same atomic number but have different neutron counts.

02 / Physical properties

Melting point

453.65 K

Boiling point

1615 K

Density

0.534 g/cm³

Atomic weight

6.94 ± 0.06

Melting points, boiling points and densities follow RSC fact boxes. Density is referenced to room temperature; consult the source for pressure and allotrope details. These are reference values, not a claim that every value was experimentally measured. Atomic weights follow CIAAW.

Physical-property source: Royal Society of Chemistry ↗ · Reviewed 24 September 2026

Standard atomic weights follow CIAAW 2024 (abridged). Brackets show an isotope mass number from IUPAC 2022, not a standard atomic weight.

03 / Atomic structure

Atomic structure

Electron configuration

[He]2s1

Oxidation states

+1

Electronegativity · Pauling

0.98

First ionisation energy

5.392 eV

Atomic radius

182 pm

04 / Where it is found

Where it is found

Brines and minerals such as spodumene.