Pa - Protactinium

Both highly radioactive and toxic, protactinium was discovered independantly by Fajans and Göhring in Germany and by Soddy, Cranston and Fleck, in Scotland in 1913. The name means 'precursor of actinium'. If this seems somewhat unimaginative, it was actually a celebration of the ability to understand what that means.

The element is used for the production of certain isotopes of uranium.

Atomic number - 91 Density g/mL 15 .4
Atomic weight u 231 .03588 Melting point K -
Bonding radius A - Boiling point K -
Atomic radius A - Heat of vaporization kJ/mol -
Ionization Potential V 5 .89 Heat of fusion kJ/mol 12 .3
Electronegativity - 1 .5 Specific heat J/gK -
The oxide is a weak base.
Crystal are orthorhombic.

Electron config. : [Rn] 5f2 6d1 7s2

Top | About | Search | Comment | PC Chemistry

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac** Rf Db Sg Bh Hs Mt 110 111 112 113
Lanthanides* Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Actinides ** Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Isotopes of Pa: Click mass number for decay process, product for element page.
213
5.3 msec
a,7.840 MeV
Ac-209
213.0 		214
17 msec
a,8.270 MeV
Ac-210
214.02074 		215
15 msec
a,8.170 MeV
Ac-211
215.01901 		216
0.20 sec
a/EC,8.100
Ac-212/Th-216
216.01910 		217
3.4 msec
a,8.490 MeV
Ac-213
217.01829 		218
0.12 msec
a,9.790 MeV
Ac-214
218.02001 		219
53 nsec
a,10.080 MeV
Ac-215
219.01988
220
0.78 usec
a/EC,9.830
Ac-216/Th-220
220.02187 		221
5.9 usec
a,9.250 MeV
Ac-217
221.02186 		222
2.9 msec
a,8.850 MeV
Ac-218
222.02372 		223
5 msec
a,8.340 MeV
Ac-219
223.02396 		224
0.79 sec
a,7.694 MeV
Ac-220
224.02561 		225
1.7 sec
a,7.390 MeV
Ac-221
225.02611 		226
1.8 min
a/EC,6.987
Ac-222/Th-226
226.02793
227
38.3 min
a/EC,6.580
Ac-223/Th-227
227.02879 		228
22 hr
a/EC,2.111
Ac-224/Th-228
228.03099 		229
1.50 da
a/EC,5.168
Ac-225/Th-229
229.03209 		230
17.4 da
a/B-/EC,1.310
Ac-226/U-230/Th-230
230.03453 		231
32760 yr
a/SF,5.149
Ac-227/?
231.03587 		232
1.31 da
B-/EC,1.337
U-232/Th-232
232.03858 		233
26.967 da
B-,1.245 MeV
U-233
233.04023
234
6.70 hr
B-,2.197 MeV
U-234
234.04330 		235
24.5 min
B-,1.410 MeV
U-235
235.04543 		236
9.1 min
B-,2.900 MeV
U-236
236.04867 		237
8.7 min
B-,2.250 MeV
U-237
237.05114 		238
2.3 min
B-/SF,3.460
U-238/?
238.05449 		MASS abund.
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass

Updated by clh on 2/6/98. This is not a publication of Phoenix College.