Li · Element 3 · Alkali metals
The lightest metal, soft enough to cut with a knife and reactive enough to be stored under oil — the element that powers almost every rechargeable device you own.
Structure
Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.
Measured values
Every bar shows where lithium sits among all 118 elements for that property.
Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.
Size, to scale
Radius 152 pm — that is 0.152 nm, so about 3289 million of them side by side would span a millimetre.
Thermal range
Lithium is liquid over a 1161 K window, from 454 K to 1615 K.
The story
Lithium, the lightest metal on Earth, has revolutionized modern technology and medicine. Named from the Greek "lithos" meaning stone, this silvery-white alkali metal was first discovered in 1817 by Johan August Arfwedson in the mineral petalite. Despite being solid, lithium is so light it floats on water - though it reacts violently upon contact.
Lithium exhibits extraordinary characteristics that set it apart from other metals. With a density of only 0.534 g/cm³, it's half as dense as water. It has the highest specific heat capacity of any solid element and the greatest temperature range between melting and boiling points of any element. Fresh lithium has a bright metallic luster but quickly tarnishes in air, forming a gray oxide coating.
As the first alkali metal, lithium is highly reactive but less so than other group 1 elements. It reacts with water to produce lithium hydroxide and hydrogen gas: 2Li + 2H₂O → 2LiOH + H₂. Unlike other alkali metals, lithium forms a stable nitride (Li₃N) when exposed to nitrogen gas, and its compounds often show covalent character due to the small size and high charge density of Li⁺ ions.
Lithium plays a crucial role in neurochemistry and mental health. Lithium salts have been used to treat bipolar disorder since 1949, making it one of the oldest psychiatric medications still in use. The metal crosses the blood-brain barrier and affects neurotransmitter function, particularly serotonin and norepinephrine pathways.
Applications
Handling
FLAMMABLE METAL - WATER REACTIVE
Lithium Fire:
Skin/Eye Contact:
Inhalation Exposure:
Medical Toxicity:
Quick answers
Lithium (symbol Li) is element 3 on the periodic table, a alkali metal in period 2, group 1. The lightest metal, soft enough to cut with a knife and reactive enough to be stored under oil — the element that powers almost every rechargeable device you own. At room temperature it is a solid.
[He] 2s¹, giving 2 occupied shells holding 2, 1 electrons respectively.Lithium melts at 453.7 K (180.5 °C) and boils at 1615 K (1341.9 °C).
The standard atomic weight of Lithium is 6.94 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.
Lithium has a density of 0.534 g/cm³. Water is 1.0 g/cm³, so a block of lithium floats.
Lithium has a Pauling electronegativity of 0.98. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). A value this low means it readily gives its outer electrons away, forming positive ions.
Lithium was discovered in 1817 by Johan August Arfwedson. It is named after greek lithos, "stone".
Lithium makes up about 20 mg/kg of the Earth's crust — uncommon, but not rare.