All practice pages/Interatomic theory/Elements
Element 3, an alkali metal
The lightest metal of all: soft enough to cut with a knife, light enough to float on oil, and the heart of the rechargeable battery in your pocket.
Period 2, group 1. The other alkali metals are tinted, and every cell opens its own article.
Lithium has 3 electrons, one for every proton, so the atom carries no charge. Below are the same 3 electrons written two ways.
1s² 2s¹
Short form: [He] 2s¹, where [He] stands for the 2 electrons helium already has.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14.
Lithium sits in period 2 and has 2 shells. The period number counts the shells.
The outer shell holds 1 electron. Those are the ones lithium can lose, gain or share, so they are the ones that decide what it bonds with. For a main-group element the group number gives that count: group 1 means 1.
One valence electron, which lithium gives up easily to form the Li⁺ ion. Like the other alkali metals, it reacts with water.
Too reactive to occur as a metal. Most comes from salty brines pumped from beneath salt flats in Chile and Argentina and evaporated in huge ponds, and from the mineral spodumene mined in Australia. Seawater holds about 0.2 parts per million.
Johan August Arfwedson found it in 1817 in the mineral petalite, from the Swedish island of Utö. It was named from the Greek lithos, stone, because it turned up in a mineral rather than in plant ash like sodium and potassium. William Thomas Brande and Humphry Davy first isolated the metal by electrolysis.
Lithium-ion batteries for phones, laptops and electric cars now use most of it. It also goes into heat-resistant glass and ceramics, long-lasting grease, and light aluminum alloys for aircraft. Lithium carbonate has treated bipolar disorder for decades.
Reacts with water to release flammable hydrogen, and damaged lithium-ion batteries can overheat and catch fire.