Element 57 · Lanthanum (La)

Lanthanum Bohr model: diagram and electrons per shell

The lanthanum Bohr model shows a lanthanum atom (La) as a small nucleus with its electrons circling it in 6 shells: 2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P. This page has a rotating 3D lanthanum Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the lanthanum Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of lanthanum (La), a simplified picture of a single lanthanum atom. Its nucleus holds 57 protons, and a neutral lanthanum atom has 57 electrons, arranged around it in 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P).

La K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 184s² 4p⁶ 4d¹⁰ O · 95s² 5p⁶ 5d¹ P · 26s²

Lanthanum Bohr model diagram

Bohr model diagram of lanthanum: a nucleus of 57 protons with 57 electrons on 6 shells, 2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P, each ring labelled with its shell letter. — The lanthanum Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P).

Lanthanum electrons per shell

A neutral lanthanum atom has 57 electrons, one for each of its 57 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P.

Electrons in each shell of the lanthanum Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	18	18	3s² 3p⁶ 3d¹⁰
N	4	18	32	4s² 4p⁶ 4d¹⁰
O	5	9	50	5s² 5p⁶ 5d¹
P	6	2	72	6s²

How the lanthanum Bohr model builds up, shell by shell

Watch the lanthanum Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P) as it forms.

Animation of the lanthanum Bohr model being built: a nucleus of 57 protons appears first, then each shell grows in around it and takes its electrons, giving 57 electrons on 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P). — The lanthanum Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P. Protons are red, neutrons yellow and electrons blue.

How to draw the lanthanum Bohr model

Find the atomic number. Lanthanum has atomic number 57, so a neutral atom has 57 protons and 57 electrons.
Draw the nucleus. Put a circle in the centre and write La in it. The 57 protons sit there with the neutrons.
Draw the shells. Sketch 6 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 18 in shell N, 9 in shell O and 2 in shell P.
Check the total. 2 + 8 + 18 + 18 + 9 + 2 = 57, the atomic number, so every electron is accounted for.

Atomic data for the lanthanum Bohr model

The numbers behind the lanthanum Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: La
Atomic number: 57
Atomic mass: 138.9055 u
Family: Lanthanides
Position: period 6 of the f-block
Block: f-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 5d¹
Shorthand: [Xe] 5d¹⁶s2
Electrons per shell: 2, 8, 18, 18, 9, 2
Outer-shell electrons: 2 in shell P

Ionisation energies

I₁: 538.1
I₂: 1067
I₃: 1850.3
I₄: 4819
I₅: 5940

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Calculated (pm): 226
Empirical (pm): 195
Covalent (pm): 180

Electronegativity and electron affinity

Electronegativity (Pauling): 1.1
Electron affinity (kJ/mol): 53

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of lanthanum

Bulk properties of lanthanum, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Silvery white
Melting point: 919.85°C (1193 K)
Boiling point: 3463.85°C (3737 K)
Density: 6.162 g/cm³
Thermal conductivity (W/m·K): 13.4
Specific heat (J/g·K): 0.195
Molar heat capacity (J/mol·K): 27.11
Heat of fusion (kJ/mol): 8.5
Heat of vaporisation (kJ/mol): 402

Abundance

Earth's crust (mg/kg): 39
Oceans (mg/L): 0

Discovery

Discovered by: Carl Gustaf Mosander
Year: 1839

Common compounds

Lanthanum nitrate LaN3O9
Lanthanum La
Lanthanum bromide Br3La
Lanthanum chloride (LaCl3) Cl3La
Lanthanum nitrate hexahydrate H12LaN3O15
Lanthanum acetate C6H9LaO6
Lanthanum trifluoride F3La
Lanthanum trihydroxide H3LaO3

Compounds listed in the PubChem database.

Main isotopes of lanthanum

Isotopes of lanthanum share the same 57 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of lanthanum: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
132	–	4.59 h	β⁺
135	–	18.91 h	β⁺
137	–	60 ky	EC
138	0.089 %	103 Gy	β⁺, β⁻
139	99.911 %	stable	–
140	–	40.289 h	β⁻

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about lanthanum

Lanthanum on the periodic table – properties, isotopes, uses and the full lanthanum page.
Lanthanides – all lanthanide elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.