003Alkali metal · Group 1 · Period 2

Lithium

Lithium (Li) is element 3, a alkali metal in the s-block — group 1, period 2. It is a solid at room temperature with 2 electron shells (2, 1) and an atomic mass of 6.94 u.

Atomic mass: 6.940 u
Phase · STP: solid
Melting: 454 K · 181 °C
Boiling: 1603 K · 1330 °C
Electronegativity: 0.98
Density: 0.534 g/cm³

Photograph — Hi-Res Images ofChemical Elements, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/lithium.php

Identity

Atomic number: 3
Standard atomic weight: 6.940 u
Category: Alkali metal
Group: 1 · Alkali metals
Period: 2
Block: s-block
Oxidation states: +1

Physical properties

Melting point: 454 K · 181 °C
Boiling point: 1603 K · 1330 °C
Density: 0.534 g/cm³
Molar heat capacity: 24.86 J/(mol·K)
Atomic radius: 182 pm
Electron affinity: 59.6326 kJ/mol

Atomic structure

3protons

4neutrons

3electrons

1valence e⁻

Noble-gas notation: [He] 2s1
Full configuration: 1s2 2s1
Electrons per shell: 2, 1

Periodic trends

Where Lithium ranks across all 118 elements.

Electronegativity0.98

Ionization energy520.2 kJ/mol

Electron affinity59.6326 kJ/mol

Density0.534 g/cm³

Atomic radius182 pm

Ionization energies

Energy to remove each successive electron (kJ/mol).

520.2

7.3k

11.8k

Successive ionization energies (kJ/mol, log scale).

Discovery

Discovered: 1817
Discovered by: Johan August Arfwedson
Named by: —
Appearance: silvery-white