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

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

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

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