Lanthanum 57

Atomic No. Order:

Alphabetic Order:

Periodic Table

Sc
21

Y
39

La
57

Ac
89

Ubu
121

Usu
171

Bbu
221

Lanthanum

Symbol

Atomic Number

Relative Atomic Mass
12C = 12.0000

138.9055(2) [Since 1985]

Atomic Radius pm

188

First Ionisation Energy
kJ mol-1

538.1

Electronegativity

1.10

Density kg m-3

6145 [298 K]

Molar Volume cm3

22.60

Thermal Conductivity
W m-1 K-1

13.5 [300 K]

Melting Point K

1194

Boiling Point K

3730

Number of Isotopes

Isotope Atomic mass/u Mole fraction

138La 137.907 108(4) 0.000 90(1)
139La 138.906 349(4) 0.999 10(1)

Inner/outer Shells

Inner/outer Orbitals

???

Algorythm of Software

2, 8, 18,

18, 9, 2

2, 8, 18,

19, 8, 2

Distribution of electrons

	s	p	d	f
1	2
2	2	6
3	2	6	10
4	2	6	10
5	2	6	1
6	2
7

	s	p	d	f
1	2
2	2	6
3	2	6	10
4	2	6	10	1
5	2	6
6	2
7

Filling Orbital

5d ¹

4f ¹

Ground State Electron Configuration

[Xe]

4d ¹⁰

5d ¹

6s ²

[Xe]

4f ¹

5p ⁶

6s ²

Ground State Electron Configuration w ith free Orbitals (n=29)

0, 0, 0, 14, 9, 6

0, 0, 0, 13, 10, 6

Ground State Electron Con figuration with compressed Orbitals (n=96)

0, 0, 0, 0, 32, 64

Singularity

182

	s	p	d	f		g	h	i	j
1	2
2	2	6
3	2	6	10
4	2	6	10	1	13
5	2	6	10	14		18
6	2	6	10	14		18	22
7
8

Term Symbol

²D _3/2

Name Derived From and
Discovery

The name derives from the Greek lanthanein for " to be hidden or to escape notice" because it hid in cerium ore and was difficult to separate from that rare earth mineral. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander (Stockholm, Sweden) in 1839. In 1842, Mosander separated his lanthanium sample into two oxides; for one of these he retained the name lanthanum and for the other he gave the name didymium (or twin).

APSIDIUM ©	Created:		2002-07-21		057.pdf
	Page update:		2004-06-20		057.pdf