La - Lanthanum

The placement of lanthanum in the d block instead of the f block of the table is controversial, and we may change, pending a review of the data. The element was discovered by Mosander in 1839 in Sweden.

Atomic number - 57 Density g/mL 6 .7
Atomic weight u 138 .9055 Melting point K 1193
Bonding radius A 1 .69 Boiling point K 3730
Atomic radius A 2 .74 Heat of vaporization kJ/mol 414
Ionization Potential V 5 .58 Heat of fusion kJ/mol 6 .2
Electronegativity - 1 .1 Specific heat J/gK 0 .19
The oxide is a strong base.
Crystal are hexagonal.

Electron config. : [Xe] 5d1 6s2


Isotopes of La: Click mass number for decay process, product for element page.


120
2.8 sec
EC/ECp,11.200
Ba-120/Cs-119
119.93805
121
5.3 sec
EC,7.900 MeV
Ba-121
120.93301
122
8.7 sec
EC/ECp,9.700
Ba-122/Cs-121
121.93075
123
17 sec
EC,6.900 MeV
Ba-123
122.92624
124
29 sec
EC,8.800 MeV
Ba-124
123.92452
125
76 sec
EC,5.600 MeV
Ba-125
124.92066
126
54 sec
EC,7.600 MeV
Ba-126
125.91937
127
5.1 min
EC,4.690 MeV
Ba-127
126.91615
128
5.0 min
EC,6.700 MeV
Ba-128
127.91540
129
11.6 min
EC,3.720 MeV
Ba-129
128.91266
130
8.7 min
EC,5.600 MeV
Ba-130
129.91232
131
59 min
EC,2.960 MeV
Ba-131
130.91011
132
4.8 hr
EC,4.710 MeV
Ba-132
131.91011
133
3.912 hr
EC,2.230 MeV
Ba-133
132.90839
134
6.45 min
EC,3.710 MeV
Ba-134
133.90849
135
19.5 hr
EC,1.200 MeV
Ba-135
134.90697
136
9.87 min
EC,2.870 MeV
Ba-136
135.90765
137
6E+4 yr
EC,1.176 MeV
Ba-137
136.90646
138 0.0902%
1.05E+11 yr
B-/EC,1.737
Ce-138/Ba-138
137.90710
139 99.9098%

Stable

138.90634
140
1.6781 da
B-,3.762 MeV
Ce-140
139.90947
141
3.92 hr
B-,2.502 MeV
Ce-141
140.91095
142
91.1 min
B-,4.505 MeV
Ce-142
141.91407
143
14.2 min
B-,3.425 MeV
Ce-143
142.91605
144
40.8 sec
B-,5.540 MeV
Ce-144
143.91959
145
24.8 sec
B-,4.120 MeV
Ce-145
144.92165
146
6.27 sec
B-,6.550 MeV
Ce-146
145.92575
147
4.015 sec
B-/B-n,4.950
Ce-147/Ce-146
146.92781
148
1.428 sec
B-/B-n,7.260
Ce-148/Ce-147
147.93219
149
1.05 sec
B-/B-n,5.500
Ce-149/Ce-148
148.93419
150
0.86 sec
B-/B-n,7.800
Ce-150/Ce-149
149.93859
152
150 nsec
B-,9.100 MeV
Ce-152
151.94610
MASS abund.
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass