Rare earth elements of the f-block
Lanthanides are 15 chemical elements with atomic numbers from 57 (lanthanum) to 71 (lutetium). They are characterized by filling of 4f orbitals and very similar chemical properties. Together with scandium and yttrium, they are called rare earth elements.
Read in glossaryNeodymium magnets are the most powerful permanent magnets in the world
Europium gives red color to TV and monitor screens
Cerium is used in lighter flints
Despite being called 'rare earth', cerium is more abundant than copper
Promethium is the only radioactive lanthanide, named after Prometheus
Lanthanides are characterized by sequential filling of 4f orbitals. Their general configuration is [Xe]4f¹⁻¹⁴5d⁰⁻¹6s². 4f electrons are shielded by outer shells, explaining similar chemical properties.
Lanthanides are quite reactive metals. They react with water, acids, and air. Powdered lanthanides can spontaneously ignite in air.
| Element | Z | Mass u | M.P. °C | B.P. °C | ρ г/см³ | EN |
|---|---|---|---|---|---|---|
La Lanthanum | 57 | 138.91 ▼ | 920 | 3464 | 6.16 | 1.10 ▼ |
Ce Cerium | 58 | 140.12 | 798 ▼ | 3424 | 6.77 | 1.12 |
Pr Praseodymium | 59 | 140.91 | 931 | 3520 ▲ | 6.77 | 1.13 |
Nd Neodymium | 60 | 144.24 | 1021 | 3074 | 7.01 | 1.14 |
Pm Promethium | 61 | 144.91 | 1042 | 3000 | 7.26 | 1.13 |
Sm Samarium | 62 | 150.40 | 1072 | 1794 | 7.52 | 1.17 |
Eu Europium | 63 | 151.96 | 822 | 1529 | 5.26 ▼ | 1.20 |
Gd Gadolinium | 64 | 157.25 | 1312 | 3273 | 7.90 | 1.20 |
Tb Terbium | 65 | 158.93 | 1356 | 3230 | 8.23 | 1.20 |
Dy Dysprosium | 66 | 162.50 | 1412 | 2567 | 8.54 | 1.22 |
Ho Holmium | 67 | 164.93 | 1474 | 2700 | 8.79 | 1.23 |
Er Erbium | 68 | 167.26 | 1529 | 2868 | 9.07 | 1.24 |
Tm Thulium | 69 | 168.93 | 1545 | 1950 | 9.32 | 1.25 |
Yb Ytterbium | 70 | 173.05 | 819 | 1196 ▼ | 6.90 | 1.10 ▼ |
Lu Lutetium | 71 | 174.97 ▲ | 1663 ▲ | 3402 | 9.84 ▲ | 1.27 ▲ |
The name 'lanthanides' comes from Greek λανθάνειν (lanthanein) — 'to hide'. This reflects the difficulty of separating these elements from each other due to their similarity. The term 'rare earth' is historical — they are not that rare.
Discovery of cerium — beginning of rare earth elements history
Carl Mosander isolated lanthanum from cerium earth
Auer von Welsbach separated 'didymium' into neodymium and praseodymium
Invention of NdFeB magnets revolutionized electronics and energy
Discovered neodymium, praseodymium, lutetium; invented gas mantle
Discovered lanthanum, erbium, and terbium
Invented NdFeB neodymium magnets in 1982