Praseodymium

Symbol: Pr
Atomic number: 59
Category: lanthanides
Group: n/a
Period: 6
Block: f
Atomic weight: 140.90765 g/mol
Electrons per shell: 2, 8, 18, 21,8, 2
CAS number: 7440-10-0
Phase: solid
Density: 6.77 kg/dm³ (near room temperature)
Melting point: 1208 K (935 °C, 1715 °F)
Boiling point: 3793 K (3520 °C, 6368 °F)
Crystal structure: hexagonal
Oxidation states: 3
Electronegativity: 1.13 (Pauling scale)
Name's origin: prasios and didymos
Name's meaning: Greek words which mean green and twin because it is used in glasses to give a green color
Facts:
- is a soft, silvery, malleable and ductile metal
- develops a green oxide coating that spalls off when exposed to air, exposing more metal to oxidation - for this reason, praseodymium should be stored under a light mineral oil or sealed in g
- is frequently misspelled as praseodynium
- is available in small quantities in Earth's crust (9.5 ppm)
- is found in the rare earth minerals monazite and bastnasite, typically comprising about 5 % of the lanthanides contained therein
- like all rare earths, praseodymium is of low to moderate toxicity
- has no known biological role
- is used in making aircraft engines, in carbon-arc lighting, in glassware making to give them a yellow color