Mendeleev's Periodic Table > La - Lanthanum

La - Lanthanum

The element was discovered by Mosander in 1839 in Sweden. Lanthanum is silvery white, malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidises rapidly when exposed to air. Cold water attacks lanthanum slowly, and hot water attacks it much more rapidly. The metal reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulphur, and with halogens.

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 (Lanthanum):

MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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
MASS abundancy Halflife Particle, Energy Decay Product(s) Isotopic Mass	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