All practice pages/Interatomic theory/Elements
Element 62, a lanthanide
The first element named, indirectly, after a person, and half of the magnets that keep working when things get hot.
Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.
Samarium has 62 electrons, one for every proton, so the atom carries no charge. Below are the same 62 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁶ 5s² 5p⁶ 6s²
Short form: [Xe] 4f⁶ 6s², where [Xe] stands for the 54 electrons xenon already has.
That list runs by shell. In the order the subshells fill it reads [Xe] 6s² 4f⁶, 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 4 here is 4s² 4p⁶ 4d¹⁰ 4f⁶, and 2 + 6 + 10 + 6 is 24.
Samarium sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones samarium can lose, gain or share, so they are the ones that decide what it bonds with.
Like the other lanthanides, it gives up three electrons to form the Sm³⁺ ion in most of its compounds.
Found in monazite and bastnäsite, mostly mined in China.
Paul-Émile Lecoq de Boisbaudran found it in 1879 in the mineral samarskite, which had been named after Vasili Samarsky-Bykhovets, a Russian mining engineer who supplied the samples. That makes samarium the first element named, by way of a mineral, after a person.
Samarium-cobalt magnets hold their strength at high temperatures and resist corrosion, so they are used in aerospace and military equipment and in some electric guitar pickups. Samarium-153 eases bone pain from cancer, samarium absorbs neutrons in reactor control rods, and samarium(II) iodide is a tool for organic chemists.