All practice pages/Interatomic theory/Elements
Element 51, a metalloid
A brittle metalloid once ground into ancient eyeliner, now mostly used to keep plastics and fabrics from catching fire.
Period 5, group 15. The other metalloids are tinted, and every cell opens its own article.
Antimony has 51 electrons, one for every proton, so the atom carries no charge. Below are the same 51 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³
Short form: [Kr] 4d¹⁰ 5s² 5p³, where [Kr] stands for the 36 electrons krypton already has.
That list runs by shell. In the order the subshells fill it reads [Kr] 5s² 4d¹⁰ 5p³, because a subshell fills by its energy, not by its shell number.
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. Shell 3 here is 3s² 3p⁶ 3d¹⁰, and 2 + 6 + 10 is 18.
Antimony sits in period 5 and has 5 shells. The period number counts the shells.
The outer shell holds 5 electrons. Those are the ones antimony 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 15 means 5.
Five valence electrons, like nitrogen and phosphorus. Antimony mostly shares electrons in covalent bonds, in the +3 or +5 state with oxygen, sulfur and chlorine.
Mined mainly as stibnite (Sb₂S₃), with China, Tajikistan and Russia supplying most of it.
Stibnite was ground into kohl, a black eye cosmetic, in ancient Egypt, and objects of antimony metal survive from the ancient world. Vannoccio Biringuccio described extracting the metal in 1540. The origin of the name is uncertain; the symbol Sb comes from its Latin name stibium.
Antimony trioxide makes flame retardants in plastics, textiles and electronics work better, and takes the largest share. Antimony hardens the lead in car batteries and bullets, and it goes into semiconductors, glass and the catalysts used to make PET plastic bottles.
Antimony and many of its compounds are toxic, in ways similar to arsenic but milder.