Protactinium
91Pa
Pr ↑ Pa ↓ (Uqt) Periodic table thorium ← protactinium → uranium
Panagway
bright, silvery metallic luster Payl:Protactinium.jpg
Kinatibuk-ang mga kinaiya
Ngalan, simbolo, kaiphan	protactinium, Pa, 91
Paglitok	/ˌproʊtækˈtɪniəm/ [[Help:Pronunciation respelling key|Plantilya:Smallcaps all-tak-Plantilya:Smallcaps all-ee-əm]]
Kategoriyang elemento	aktinido
Group, period, block	n/a, 7, f
Gibug-aton sa atomo	231.03588
Kontorno sa elektron	[Rn] 5f2 6d1 7s2 2, 8, 18, 32, 20, 9, 2
History
Prediction	Dmitri Mendeleev (1869)
Pagkadiskobre	William Crookes (1900)
First isolation	William Crookes (1900)
Named by	Otto Hahn and Lise Meitner (1917–8)
Physical properties
Phase	magahi
Density (near r.t.)	15.37 g·cm−3
Melting point	1841 K, 1568 °C, 2854 °F
Boiling point	? 4300 K, ? 4027 °C, ? 7280 °F
Heat of fusion	12.34 kJ·mol−1
Heat of vaporization	481 kJ·mol−1
Atomic properties
Oxidation states	2, 3, 4, 5 (weakly basic oxide)
Electronegativity	1.5 (Pauling scale)
Ionization energies	1st: 568 kJ·mol−1
Atomic radius	163 pm
Covalent radius	200 pm
Miscellanea
Crystal structure	tetragonal[1]
Magnetic ordering	paramagnetic[2]
Electrical resistivity	(0 °C) 177 nΩ·m
Thermal conductivity	47 W·m−1·K−1
CAS registry number	7440-13-3
Most stable isotopes
Main article: Isotopes of protactinium
iso NA half-life DM DE (MeV) DP 229Pa syn 1.5 d ε 0.311 229Th 230Pa syn 17.4 d ε 1.310 230Th 231Pa ~100% 3.276×104 y α 5.150 227Ac 232Pa syn 1.31 d β− 1.337 232U 233Pa trace 26.967 d β− 0.5701 233U 234mPa trace 1.17 min β− 2.29 234U 234Pa trace 6.75 h β− 2.195 234U
v t e · r

Ang protactinyo (Iningles protactinium) mao ang elementong kimiko sa talaang peryodiko nga may simbolo nga Pa ug kaiphan nga atomik 91. Ang protactinyo mao ang aktinido.

1. ↑ Donohue, J. (1959). "On the crystal structure of protactinium metal". Acta Crystallographica. 12 (9): 697. doi:10.1107/S0365110X59002031.
2. ↑ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.