Multi-Model Element Hub

Fermium Electron Configuration,
Atomic Structure & SPDF Orbitals

Complete multi-model analysis of Fermium (Fm). Explore its [Rn] 5f¹² 7s² electron configuration, atomic structure, and how its 3 valence electrons drive its exact chemical properties.

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Fact-Checked Scientific Data

Electron configurations and valence mechanics verified against PubChem API & IUPAC standards.

What is the Electron Configuration of Fermium?

Snippet: To fundamentally understand Fermium, you must examine its electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹² 7s². Being an f-block actinide, this chemical element relies on its shorthand valence arrangement ([Rn] 5f¹² 7s²) to form high-strength bonds. With precisely 100 electrons orbiting the atomic nucleus, Fermium sits comfortably in period 7, group 3.

Fermium Bohr Model Explained

The Bohr model of Fermium provides a clear, 2D planetary visualization of its 100 electrons dynamically orbiting the central nucleus. By stacking its electrons outward into 7 distinct rings—filling in the specific pattern of 2, 8, 18, 32, 30, 8, 2—the Bohr diagram fundamentally exposes why Fermium has 3 valence electrons available for reactivity.

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Live Shell Distribution:2 – 8 – 18 – 32 – 30 – 8 – 2

While the interactive Bohr visualizer above demonstrates the dynamic movement, fundamentally the Bohr model maps Fermium's structure in concentric rings. It gives an immediate intuitive grasp of why Fermium possesses 3 valence electrons without needing complex wave mechanics.

SPDF Orbital Model of Fermium

The SPDF quantum orbital model explains Fermium's true three-dimensional structure. Dictated by the Aufbau principle, Fermium's 100 electrons populate spherical (s), dumbbell (p), clover (d), or complex (f) probability clouds in a strict energy sequence: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹² 7s². It terminates precisely in the f-block.

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Spherical, max 2e⁻

Lobed, max 6e⁻

Cloverleaf, max 10e⁻

Complex, max 14e⁻

The SPDF structure determines far more than just location; it defines Fermium's magnetic footprint, its ionization energy curves, and precisely how it physically overlaps with neighboring atoms to form complex covalent or ionic bonds. Our interactive SPDF diagram above allows you to see this subshell hierarchy mathematically stacked from lowest to highest energy states.

Electron Configuration Breakdown

Full Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹² 7s²
Noble Gas Shorthand: [Rn] 5f¹² 7s²
Total Shells: 7 shells containing (2, 8, 18, 32, 30, 8, 2) electrons respectively.
Terminal Block: The final electron lands in the f-block, characterizing it as a actinide.

Valence Electrons in Fermium

Valence Electrons

3 Valence Electrons

Fermium tends to donate electrons to achieve a stable octet, driving its chemical reactivity.

Group 3F-Block

Given that Fermium possesses exactly 3 valence electrons in its absolute outermost shell, it is heavily inclined to donate these electrons to form electropositive cations.

Fermium Atomic Structure Table

Atomic Number (Z) / Protons

100

Total Electrons

100

Neutrons (Most common isotope)

157

Atomic Mass

257 u

Pauling Electronegativity

1.3

Primary Oxidation States

Why Fermium Behaves This Way

Also discovered in the Ivy Mike thermonuclear bomb test debris in 1952. Named after Enrico Fermi, father of nuclear reactor design. Fermium has no practical applications beyond basic research; quantities are too minute for bulk use. The heaviest element that can be produced in appreciable quantities via nuclear reactor neutron bombardment.

Real-World Industrial & Biological Context

Fundamental Physics ResearchActinide Model for Electronic StructureTarget for Mendelevium ProductionNuclear ScienceIsotope Mass Measurements

Comparison with Neighbour Elements

When measured against its immediate periodic neighbours, Fermium demonstrates a calculated structural momentum. Its atomic radius (190 pm) and electronegativity (1.3) represent a critical transition point across Period 7.

Previous Element

Einsteinium (Z=99)

Next Element

Mendelevium (Z=101)

Fermium Orbital Build Challenge

Click orbitals in Aufbau order to build the correct electron configuration. Earn 100 XP per correct answer.

Orbital Build Challenge

Construct the complete SPDF electron configuration for Fermium (100 electrons) in correct Aufbau order. Click orbitals in sequence.

Click orbitals below to build configuration…

Element Comparison Matrix

Compare the atomic radius, electronegativity, and configurations of any two elements.

Element Comparison Tool

Compare any two elements side-by-side across all key atomic properties, electron configurations, and valence electrons.

Element A

Element B

Property

Sodium (Na)

Potassium (K)

Atomic Number

Periodic Trends Analysis

Visualize overarching periodic trends like Ionization Energy and Atomic Mass across all 118 elements.

Periodic Trends Visualizer

Explore how key atomic properties trend across a period or group. Understanding trends is essential for predicting chemical reactivity and bonding.

Property

Period

↑ Electronegativity

0.98 Pauling

1.57 Pauling

2.04 Pauling

2.55 Pauling

3.04 Pauling

3.44 Pauling

3.98 Pauling

Electronegativity Trend — Period 2: Electronegativity generally increases left-to-right across a period as nuclear charge increases with no new shielding electron shells added.

Frequently Asked Questions about Fermium

What is the exact electron configuration of Fermium?

The complete, full-length electron configuration of Fermium is written universally as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹² 7s². Using standard noble-gas core condensation, its shorthand notation is abbreviated to [Rn] 5f¹² 7s².

How many valence electrons does Fermium contain?

Based on its position in group 3 of the periodic table, Fermium possesses exactly 3 valence electrons in its absolute outermost shell. These specific electrons are strictly responsible for dictating its chemical reactivity, bonding geometry, and physical phase.

What is the Bohr shell distribution for Fermium?

The classical Bohr model of Fermium illustrates its 100 electrons distributed sequentially across 7 major energy shells. The exact electron count per shell, from the innermost ring stretching outward, is: 2, 8, 18, 32, 30, 8, 2.

What are the physical and chemical properties of Fermium?

Fermium is a actinide with a measured atomic mass of 257.000 u. It has an atomic radius of 190 pm and an electronegativity rating of 1.3. It typically exhibits oxidation states involving 3.

Why is Fermium placed in the f-block of the periodic table?

Fermium is classified strictly as a f-block element because its absolute highest-energy (terminating) electron physically resides within an f-subshell according to the quantum mechanical Aufbau filling principle.

How many total protons, neutrons, and electrons are inside a neutral Fermium atom?

A perfectly neutral atom of Fermium contains exactly 100 protons in its dense nucleus and 100 electrons orbiting it. While the neutron count varies dynamically by isotopic mass, its most abundant, naturally occurring isotope possesses approximately 157 neutrons.

Is Fermium chemically reactive or stable?

Operating with 3 valence electrons, Fermium's reactivity is determined by its drive to achieve a noble-gas octet. Because its outer shell is incomplete, it is chemically reactive and violently seeks to form bonds with other elements.

What are the most common real-world uses of Fermium?

Due to its specific atomic structure and electron mechanics, Fermium is heavily utilized in Fundamental Physics Research, Actinide Model for Electronic Structure, Target for Mendelevium Production. Its macroscopic industrial properties are a direct physical manifestation of its microscopic electron configuration.

Does Fermium follow the standard Aufbau principle rules?

Yes. Fermium systematically and predictably follows the standard Madelung Aufbau energy-filling rules without any abnormal electron migrations.

What is the symbol and atomic number of Fermium?

The internationally recognized chemical symbol for Fermium is Fm, uniquely identifying it alongside its absolute atomic number of 100 across all global chemical databases like IUPAC and PubChem.

Electronic Configuration of All 118 Elements

[Ar] 3d¹⁰ 4s² 4p¹3 ve

GermaniumZ=32

[Ar] 3d¹⁰ 4s² 4p²4 ve

ArsenicZ=33

[Ar] 3d¹⁰ 4s² 4p³5 ve

SeleniumZ=34

[Ar] 3d¹⁰ 4s² 4p⁴6 ve

BromineZ=35

[Ar] 3d¹⁰ 4s² 4p⁵7 ve

KryptonZ=36

[Ar] 3d¹⁰ 4s² 4p⁶8 ve

[Kr] 4d¹⁰ 5s² 5p¹3 ve

TinZ=50

[Kr] 4d¹⁰ 5s² 5p²4 ve

AntimonyZ=51

[Kr] 4d¹⁰ 5s² 5p³5 ve

TelluriumZ=52

[Kr] 4d¹⁰ 5s² 5p⁴6 ve

IodineZ=53

[Kr] 4d¹⁰ 5s² 5p⁵7 ve

XenonZ=54

[Kr] 4d¹⁰ 5s² 5p⁶8 ve

[Xe] 4f¹⁴ 5d¹ 6s²3 ve

HafniumZ=72

[Xe] 4f¹⁴ 5d² 6s²4 ve

TantalumZ=73

[Xe] 4f¹⁴ 5d³ 6s²5 ve

TungstenZ=74

[Xe] 4f¹⁴ 5d⁴ 6s²6 ve

RheniumZ=75

[Xe] 4f¹⁴ 5d⁵ 6s²7 ve

OsmiumZ=76

[Xe] 4f¹⁴ 5d⁶ 6s²8 ve

IridiumZ=77

[Xe] 4f¹⁴ 5d⁷ 6s²9 ve

PlatinumZ=78

[Xe] 4f¹⁴ 5d⁹ 6s¹10 ve

GoldZ=79

[Xe] 4f¹⁴ 5d¹⁰ 6s¹11 ve

MercuryZ=80

[Xe] 4f¹⁴ 5d¹⁰ 6s²12 ve

ThalliumZ=81

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹3 ve

LeadZ=82

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p²4 ve

BismuthZ=83

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³5 ve

PoloniumZ=84

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁴6 ve

AstatineZ=85

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵7 ve

RadonZ=86

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶8 ve

[Rn] 5f¹⁴ 7s² 7p¹3 ve

RutherfordiumZ=104

[Rn] 5f¹⁴ 6d² 7s²4 ve

DubniumZ=105

[Rn] 5f¹⁴ 6d³ 7s²5 ve

SeaborgiumZ=106

[Rn] 5f¹⁴ 6d⁴ 7s²6 ve

BohriumZ=107

[Rn] 5f¹⁴ 6d⁵ 7s²7 ve

HassiumZ=108

[Rn] 5f¹⁴ 6d⁶ 7s²8 ve

MeitneriumZ=109

[Rn] 5f¹⁴ 6d⁷ 7s²9 ve

DarmstadtiumZ=110

[Rn] 5f¹⁴ 6d⁹ 7s¹10 ve

RoentgeniumZ=111

[Rn] 5f¹⁴ 6d¹⁰ 7s¹11 ve

CoperniciumZ=112

[Rn] 5f¹⁴ 6d¹⁰ 7s²12 ve

NihoniumZ=113

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p¹3 ve

FleroviumZ=114

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p²4 ve

MoscoviumZ=115

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³5 ve

LivermoriumZ=116

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁴6 ve

TennessineZ=117

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵7 ve

OganessonZ=118

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶8 ve

Element Dictionary — All 118 Elements

1HHydrogen 2HeHelium 3LiLithium 4BeBeryllium 5BBoron 6CCarbon 7NNitrogen 8OOxygen 9FFluorine 10NeNeon 11NaSodium 12MgMagnesium 13AlAluminum 14SiSilicon 15PPhosphorus 16SSulfur 17ClChlorine 18ArArgon 19KPotassium 20CaCalcium 21ScScandium 22TiTitanium 23VVanadium 24CrChromium 25MnManganese 26FeIron 27CoCobalt 28NiNickel 29CuCopper 30ZnZinc 31GaGallium 32GeGermanium 33AsArsenic 34SeSelenium 35BrBromine 36KrKrypton 37RbRubidium 38SrStrontium 39YYttrium 40ZrZirconium 41NbNiobium 42MoMolybdenum 43TcTechnetium 44RuRuthenium 45RhRhodium 46PdPalladium 47AgSilver 48CdCadmium 49InIndium 50SnTin 51SbAntimony 52TeTellurium 53IIodine 54XeXenon 55CsCesium 56BaBarium 57LaLanthanum 58CeCerium 59PrPraseodymium 60NdNeodymium 61PmPromethium 62SmSamarium 63EuEuropium 64GdGadolinium 65TbTerbium 66DyDysprosium 67HoHolmium 68ErErbium 69TmThulium 70YbYtterbium 71LuLutetium 72HfHafnium 73TaTantalum 74WTungsten 75ReRhenium 76OsOsmium 77IrIridium 78PtPlatinum 79AuGold 80HgMercury 81TlThallium 82PbLead 83BiBismuth 84PoPolonium 85AtAstatine 86RnRadon 87FrFrancium 88RaRadium 89AcActinium 90ThThorium 91PaProtactinium 92UUranium 93NpNeptunium 94PuPlutonium 95AmAmericium 96CmCurium 97BkBerkelium 98CfCalifornium 99EsEinsteinium 100FmFermium 101MdMendelevium 102NoNobelium 103LrLawrencium 104RfRutherfordium 105DbDubnium 106SgSeaborgium 107BhBohrium 108HsHassium 109MtMeitnerium 110DsDarmstadtium 111RgRoentgenium 112CnCopernicium 113NhNihonium 114FlFlerovium 115McMoscovium 116LvLivermorium 117TsTennessine 118OgOganesson

Technical AuthorFact CheckedLast Reviewed: April 2026

Toni Tuyishimire

Principal Software EngineerScience & EdTech Systems

Toni is specialized in high-performance computational tools and complex STEM visualizations. Through Toni Tech Solution, he architects scientifically accurate, deterministic software systems designed to educate and empower global digital audiences.