Element 100 · Fermium (Fm)

Fermium Bohr model: diagram and electrons per shell

The fermium Bohr model shows a fermium atom (Fm) as a small nucleus with its electrons circling it in 7 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q. This page has a rotating 3D fermium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the fermium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of fermium (Fm), a simplified picture of a single fermium atom. Its nucleus holds 100 protons, and a neutral fermium atom has 100 electrons, arranged around it in 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q).

Fm K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 324s² 4p⁶ 4d¹⁰ 4f¹⁴ O · 305s² 5p⁶ 5d¹⁰ 5f¹² P · 86s² 6p⁶ Q · 27s²

Fermium Bohr model diagram

Bohr model diagram of fermium: a nucleus of 100 protons with 100 electrons on 7 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q, each ring labelled with its shell letter. — The fermium 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, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q).

Fermium electrons per shell

A neutral fermium atom has 100 electrons, one for each of its 100 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q.

Electrons in each shell of the fermium 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	32	32	4s² 4p⁶ 4d¹⁰ 4f¹⁴
O	5	30	50	5s² 5p⁶ 5d¹⁰ 5f¹²
P	6	8	72	6s² 6p⁶
Q	7	2	98	7s²

How the fermium Bohr model builds up, shell by shell

Watch the fermium 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, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q) as it forms.

Animation of the fermium Bohr model being built: a nucleus of 100 protons appears first, then each shell grows in around it and takes its electrons, giving 100 electrons on 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q). — The fermium 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, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q. Protons are red, neutrons yellow and electrons blue.

How to draw the fermium Bohr model

Find the atomic number. Fermium has atomic number 100, so a neutral atom has 100 protons and 100 electrons.
Draw the nucleus. Put a circle in the centre and write Fm in it. The 100 protons sit there with the neutrons.
Draw the shells. Sketch 7 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, 32 in shell N, 30 in shell O, 8 in shell P and 2 in shell Q.
Check the total. 2 + 8 + 18 + 32 + 30 + 8 + 2 = 100, the atomic number, so every electron is accounted for.

Atomic data for the fermium Bohr model

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

Identity

Symbol: Fm
Atomic number: 100
Atomic mass: [257] u
Family: Actinides
Position: period 7 of the f-block
Block: f-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹²
Shorthand: [Rn] 5f¹² 7s²
Electrons per shell: 2, 8, 18, 32, 30, 8, 2
Outer-shell electrons: 2 in shell Q

Ionisation energies

I₁: 627

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

Electronegativity and electron affinity

Electronegativity (Pauling): 1.3
Electron affinity (kJ/mol): 33.96

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of fermium

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

Physical properties

Phase at room conditions: Solid
Melting point: 1526.85°C (1800 K)

Discovery

Discovered by: Lawrence Berkeley National Laboratory
Year: 1952

Common compounds

Fermium Fm
Fermium-254 Fm
Fermium-255 Fm
Fermium-257 Fm
Fermium-252 Fm
Fermium-253 Fm
(E)-6-[4-[1-[[5-[2-[3-[2-[2-(2-acetamidoethoxy)ethoxy]ethoxy]propanoylamino]ethyl]-1,4-dioxonaphthalen-2-yl]methoxycarbonylamino]-2,2,2-trifluoroethoxy]-6-methoxy-7-methyl-3-oxo-1H-2-benzofuran-5-yl]-4-methylhex-4-enoic acid;fermium C44H52F3FmN3O15
3-[1-[tert-butyl(dimethyl)silyl]oxy-2-[6-[(E)-3-[1-[[4-[[2-carboxy-2-(9H-fluoren-9-ylmethoxycarbonylamino)ethyl]disulfanyl]phenyl]methoxycarbonylamino]-2,2,2-trifluoroethoxy]undec-1-enyl]-2-pyridinyl]ethyl]benzoic acid;fermium C59H70F3FmN3O10S2Si

Compounds listed in the PubChem database.

Main isotopes of fermium

Isotopes of fermium share the same 100 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of fermium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
251	–	5.3 h	β⁺, α
252	–	25.39 h	α, SF, 2β⁺
253	–	3 d	EC, α
254	–	3.24 h	α, SF
255	–	20.07 h	α, SF
257	–	100.5 d	α, SF

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

More about fermium

Fermium on the periodic table – properties, isotopes, uses and the full fermium page.
Actinides – all actinide elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.