Element 68 · Erbium (Er)

Erbium Bohr model: diagram and electrons per shell

The erbium Bohr model shows a erbium atom (Er) as a small nucleus with its electrons circling it in 6 shells: 2 in shell K, 8 in shell L, 18 in shell M, 30 in shell N, 8 in shell O and 2 in shell P. This page has a rotating 3D erbium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the erbium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of erbium (Er), a simplified picture of a single erbium atom. Its nucleus holds 68 protons, and a neutral erbium atom has 68 electrons, arranged around it in 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 30 in shell N, 8 in shell O and 2 in shell P).

Er K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 304s² 4p⁶ 4d¹⁰ 4f¹² O · 85s² 5p⁶ P · 26s²

Erbium Bohr model diagram

Bohr model diagram of erbium: a nucleus of 68 protons with 68 electrons on 6 shells, 2 in shell K, 8 in shell L, 18 in shell M, 30 in shell N, 8 in shell O and 2 in shell P, each ring labelled with its shell letter. — The erbium 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, 30 in shell N, 8 in shell O and 2 in shell P).

Erbium electrons per shell

A neutral erbium atom has 68 electrons, one for each of its 68 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 30 in shell N, 8 in shell O and 2 in shell P.

Electrons in each shell of the erbium 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	30	32	4s² 4p⁶ 4d¹⁰ 4f¹²
O	5	8	50	5s² 5p⁶
P	6	2	72	6s²

How the erbium Bohr model builds up, shell by shell

Watch the erbium 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, 30 in shell N, 8 in shell O and 2 in shell P) as it forms.

Animation of the erbium Bohr model being built: a nucleus of 68 protons appears first, then each shell grows in around it and takes its electrons, giving 68 electrons on 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 30 in shell N, 8 in shell O and 2 in shell P). — The erbium 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, 30 in shell N, 8 in shell O and 2 in shell P. Protons are red, neutrons yellow and electrons blue.

How to draw the erbium Bohr model

Find the atomic number. Erbium has atomic number 68, so a neutral atom has 68 protons and 68 electrons.
Draw the nucleus. Put a circle in the centre and write Er in it. The 68 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, 30 in shell N, 8 in shell O and 2 in shell P.
Check the total. 2 + 8 + 18 + 30 + 8 + 2 = 68, the atomic number, so every electron is accounted for.

Atomic data for the erbium Bohr model

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

Identity

Symbol: Er
Atomic number: 68
Atomic mass: 167.2593 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 4f¹²
Shorthand: [Xe] 4f¹² 6s²
Electrons per shell: 2, 8, 18, 30, 8, 2
Outer-shell electrons: 2 in shell P

Ionisation energies

I₁: 589.3
I₂: 1150
I₃: 2194
I₄: 4120

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): 175
Covalent (pm): 165

Electronegativity and electron affinity

Electronegativity (Pauling): 1.24
Electron affinity (kJ/mol): 30.1

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of erbium

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

Physical properties

Phase at room conditions: Solid
Appearance: Silvery white
Melting point: 1528.85°C (1802 K)
Boiling point: 2867.85°C (3141 K)
Density: 9.066 g/cm³
Specific heat (J/g·K): 0.168
Molar heat capacity (J/mol·K): 28.12
Heat of vaporisation (kJ/mol): 317

Abundance

Earth's crust (mg/kg): 3.5
Oceans (mg/L): 0

Discovery

Discovered by: Carl Gustaf Mosander
Year: 1843

Common compounds

Erbium Er
Erbium trifluoride ErF3
Erbium citrate C6H5ErO7
Erbium chloride Cl3Er
Erbium nitride (ErN) ErN
Erbium iodide (ErI3) ErI3
Erbium oxalate hydrate C2H2ErO5+
Nitric acid, erbium(3+) salt (3:1) ErN3O9

Compounds listed in the PubChem database.

Main isotopes of erbium

Isotopes of erbium share the same 68 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of erbium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
162	0.139 %	stable	α, 2β⁺
164	1.601 %	stable	α, 2β⁺
166	33.503 %	stable	–
167	22.869 %	stable	–
168	26.978 %	stable	–
170	14.91 %	stable	2β⁻, α

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

More about erbium

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