Symbol: Pa
Atomic number: 91
Category: actinides
Group: n/a
Period: 7
Block: f
Atomic weight: 231.03588 g/mol
Electrons per shell: 2, 8, 18, 32, 20, 9, 2
CAS number: 7440-13-3
Phase: solid
Density: 15.37 kg/dm3 (near room temperature)
Melting point: 1841 K (1568 C, 2854 F)
Boiling point: 4300 K (4027 C, 7280 F)
Crystal structure: orthorhombic
Oxidation states: 2, 3, 4, 5
Electronegativity: 1.5 (Pauling scale)
Name's origin: protoactinium
Name's meaning: means 'first actinium' as its first product is the element actinium
- is a silver metallic element that belongs to the actinoid group, with a bright metallic luster that it retains for some time in the air
- due to its scarcity, high radioactivity, and toxicity, there are currently no uses for protactinium outside of basic scientific research
- twenty-nine radioisotopes of protactinium have been characterized, with the most stable being protactinium-231 with a half life of 32760 years
- is both toxic and highly radioactive
- requires precautions similar to those used when handling plutonium
- its most common ore, pitchblende, contains about 0.1 ppm of protactinium