What Is Lithium?
Lithium is a chemical element with the symbol Li and atomic number 3, classified among the alkali metals in Group 1 of the periodic table.
The lightest solid element. Powers modern rechargeable batteries and used in psychiatric medication.
As a alkali metal in Period 2 and Group 1 (Alkali Metals), lithium's placement on the table reflects its electron configuration of [He] 2s¹, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Lithium is located in Period 2, where elements fill their second electron shell.
Within that row, lithium sits in Group 1 (Alkali Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Lithium has an atomic mass of 6.941 u and a density of 0.534 g/cm³. Its melting point is 180.5°C and its boiling point is 1342°C.
Lithium is soft enough to be cut with a knife and never appears as a free element in nature, since it reacts too readily with moisture and oxygen in the air.
Electron Configuration Explained
Lithium's electron configuration is [He] 2s¹, describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine lithium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Lithium was formally discovered in 1817, J. Arfwedson, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Lithium Used For?
Lithium's specific properties make it useful in several applications, including:
- Li-ion batteries
- Psychiatric medication
- Ceramics & glass
- Nuclear reactors
- Grease lubricants
These uses reflect lithium's underlying classification as a alkali metal, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Lithium
- Lithium is so light it can float on water — but reacts violently when it touches the surface.
- Lithium is element number 3 on the periodic table, in Period 2 and Group 1.
- Its standard atomic mass is 6.941 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Lithium's atomic number?
Lithium has atomic number 3.
What is Lithium's chemical symbol?
Lithium's symbol is Li.
What group and period is Lithium in?
Lithium is in Period 2, Group 1 (Alkali Metals).
What is Lithium's atomic mass?
Lithium's standard atomic mass is 6.941 u.