Holmium

Symbol: Ho
Atomic number: 67
Category: lanthanides
Group: n/a
Period: 6
Block: f
Atomic weight: 164.93032 g/mol
Electrons per shell: 2, 8, 18, 29, 8, 2
CAS number: 7440-60-0
Phase: solid
Density: 8.79 kg/dm³ (near room temperature)
Melting point: 1734 K (1461 °C, 2662 °F)
Boiling point: 2993 K (2720 °C, 4928 °F)
Crystal structure: hexagonal
Oxidation states: 3
Electronegativity: 1.23 (Pauling scale)
Name's origin: Holmia
Name's meaning: the Latin name of Stockholm - the discoverer's home town
Facts:
- is a relatively soft and malleable silvery-white metallic element
- is stable in dry air at room temperature
- is found in the minerals monazite and gadolinite, not as a free element
- quickly oxidizes in moist air, forming a yellowish oxide
- is commercially extracted via ion-exchange from monazite sand (0.05% holmium) but is still difficult to separate from other rare earths
- its estimated abundance in the Earth's crust is 1.3 mg/kg
- plays no biological role in humans but its salts are able to stimulate metabolism
- as with other rare earths, appears to have a low degree of acute toxicity
- because of its magnetic properties, holmium has been used to create the strongest artificially-generated magnetic fields when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator)
- ince it can absorb nuclear fission-bred neutrons, the element is also used in nuclear control rods
- is also used as a yellow or red glass coloring