All practice pages/Interatomic theory/Elements
Element 64, a lanthanide
The metal that makes MRI scans sharper, and one that turns magnetic on a cold day.
Period 6, in the lanthanide row set below the main table. The other lanthanides are tinted, and every cell opens its own article.
Gadolinium has 64 electrons, one for every proton, so the atom carries no charge. Below are the same 64 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 5d¹ 6s²
Short form: [Xe] 4f⁷ 5d¹ 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 4f⁷ 5d¹, 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 4f⁷, and 2 + 6 + 10 + 7 is 25.
Gadolinium sits in period 6 and has 6 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones gadolinium can lose, gain or share, so they are the ones that decide what it bonds with.
Gadolinium gives up three electrons to form Gd³⁺, which keeps seven unpaired f electrons. Those unpaired electrons make it strongly magnetic, the property MRI contrast agents rely on.
Found in monazite and bastnäsite, mostly mined in China.
Jean Charles Galissard de Marignac detected it in 1880, and Paul-Émile Lecoq de Boisbaudran separated its oxide in 1886. It was named after the mineral gadolinite, which honors Johan Gadolin, the Finnish chemist who first analyzed ore from Ytterby.
Gadolinium compounds injected before an MRI scan make blood vessels and tumors stand out. Gadolinium absorbs neutrons better than any other stable element, so it helps control some nuclear reactors, and it goes into phosphors, magnetic refrigeration research and data storage.