Ho
Interactive Shell Diagram

Holmium Bohr Model, Electron Shell Diagram

Visualize the exact electron shell distribution of Holmium (Ho). Its 67 total electrons orbit the microscopic nucleus across 6 quantum energy shells in the specific mathematical pattern 2 – 8 – 18 – 29 – 8 – 2.

Atomic Number: Z = 67Symbol: HoShells: 6Shell Pattern: 2-8-18-29-8-2Valence e⁻: 3

Live Bohr Shell Diagram

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Shell Distribution:2 – 8 – 18 – 29 – 8 – 2

Holmium Nuclear Composition

Protons, neutrons, and electrons at a glance

Protons

67

Positive charge carriers in the nucleus

Neutrons

98

Neutral mass carriers in the nucleus

Electrons

67

Across 6 shells: 2-8-18-29-8-2

Detailed Bohr Model Analysis

Holmium's traditional Bohr model diagram provides a spectacular two-dimensional blueprint of its subatomic structure. By plotting its 67 negatively charged electrons rotating around a positively charged nucleus (containing 67 protons and approximately 98 neutrons), we can visually decrypt its chemical properties.

Across its 6 electron shells, Holmium distributes its electrons in the following exact hierarchical sequence, from the innermost ring outward: 2 – 8 – 18 – 29 – 8 – 2.

Applying the Bohr Rules to Holmium

The Bohr model, introduced by Niels Bohr in 1913, radically changed our understanding of atomic structure by proposing that electrons orbit the nucleus in strictly quantized circular energy levels (or 'shells'). For Holmium, we apply the 2n² rule, which states that the maximum electron capacity of any given shell is determined by two times the shell number (n) squared.

In the case of Holmium, its 67 total electrons stack outward from the nucleus. The innermost K-shell (n=1) holds 2 electrons. The L-shell (n=2) holds 8. This stacking continues geometrically until we map the entire 2 – 8 – 18 – 29 – 8 – 2 sequence. Because Holmium is a high-mass transuranic or deep-period element, its inner shells are packed with immense density—holding up to 32 electrons in a single shell. This massive inner core creates a powerful electrostatic shield, severely shielding the outermost electrons from the nucleus and introducing complex relativistic contraction.

The Role of Holmium's Valence Electrons

When analyzing the Bohr model of Holmium, the absolute most critical ring is the outermost shell. This layer holds exactly 3 valence electrons.

In chemistry, the core electrons (the inner rings) are chemically inert. They do not participate in bonding. All chemical reactivity, covalent sharing, and ionic transfers are conducted exclusively by the valence electrons. Because Holmium has 3 valence electrons, it inherently seeks to achieve a stable "octet" (a full outer shell of 8 electrons, or 2 for lightweight elements). Because it has fewer than 4 valence electrons, Holmium generally behaves as an electron donor. It prefers to shed its outer electrons completely, dropping down to the beautifully stable full shell beneath it, typically forming an electropositive cation.

Bohr Shell Rules (Quick Reference)

  • 2n² Rule: Shell n holds a maximum of 2n² electrons.
  • Octet Rule: The outermost (valence) shell holds a max of 8 electrons for chemical stability.
  • Aufbau Order: Electrons fill from innermost shell outward.
  • Valence = Reactivity: The electrons in the last shell dictate how the element bonds.

Chemical & Physical Overview

The element Holmium, represented universally by the chemical symbol Ho, holds the atomic number 67. This means that a standard neutral atom of Holmium possesses exactly 67 protons within its dense nucleus, orbited precisely by 67 electrons. With a standard atomic weight of approximately 164.930 atomic mass units (u), Holmium is classified fundamentally as a lanthanide.

From a periodic standpoint, Holmium resides in Period 6 and Group 3 of the periodic table, placing it firmly within the f-block. The overarching category of an element—whether it behaves as an alkali metal, a halogen, a noble gas, or a transition metal—is determined exclusively by how these electrons fill the available quantum shells.

Diving deeper into its physical footprint, Holmium exhibits a calculated atomic radius of 216 picometers (pm). When attempting to physically remove an electron from its outermost shell, it requires a primary ionization energy of 6.022 eV. Furthermore, its tendency to attract shared electrons in a covalent chemical bond—known as its electronegativity—measures at 1.23 on the Pauling scale. These specific subatomic metrics (radius, ionization, and electron affinity) combine to define exactly how Holmium interacts, bonds, and reacts with every other chemical element in the observable universe.

Atomic Properties — Holmium

Atomic Mass

164.93 u

Electronegativity

1.23 (Pauling)

Block / Group

F-block, Group 3

Period

Period 6

Atomic Radius

216 pm

Ionization Energy

6.022 eV

Electron Affinity

0.5 eV

Category

Lanthanide

Oxidation States

+3

Real-World Applications

Ho:YAG Laser (Kidney Stone Surgery)Strongest Artificial Magnets (Pole Pieces)Spectrophotometer CalibrationNuclear Reactor Burnable PoisonSolid-State Lasers

Real-World Applications & Industrial Uses

The distinct electronic structure of Holmium directly empowers its functionality in the physical world. Its specific combination of atomic radius, electron affinity, and valence shell configuration makes it absolutely indispensable across modern industry, biological systems, and advanced technology.

Here are the primary real-world applications of Holmium:

  • Ho:YAG Laser (Kidney Stone Surgery): Its baseline chemical reactivity makes it specifically suited for this primary role.
  • Strongest Artificial Magnets (Pole Pieces): Used heavily in advanced manufacturing and chemical processing.
  • Spectrophotometer Calibration
  • Nuclear Reactor Burnable Poison
  • Solid-State Lasers

    Without the specific quantum mechanics occurring microscopically within Holmium's electron cloud, these macroscopic technologies and biological processes would fundamentally fail to operate.

  • Did You Know?

    Holmium has the highest magnetic moment of any naturally occurring element. The Ho:YAG laser (2.1 μm) is widely used in minimally invasive urology (laser lithotripsy for kidney stones) and soft tissue surgery. Holmium is used in calibration filters for spectrophotometers.

    Shell-by-Shell Capacity Table

    How each of Holmium's 6 shells compare to their theoretical maximum

    ShellSymbolElectrons (This Element)Max Capacity (2n²)Fill %
    1K (n=1)22
    100%
    2L (n=2)88
    100%
    3M (n=3)1818
    100%
    4N (n=4)2932
    91%
    5O (n=5)850
    16%
    6P (n=6)272
    3%

    Shell Comparison: Holmium vs Neighbors

    ← Previous Element

    Dy

    Dysprosium

    Z=66

    2-8-18-28-8-2 shells

    View Bohr Model

    ⬤ Current

    Ho

    Holmium

    Z=67

    2-8-18-29-8-2 shells

    Next Element →

    Er

    Erbium

    Z=68

    2-8-18-30-8-2 shells

    View Bohr Model

    Frequently Asked Questions — Holmium Bohr Model

    Authoritative References

    The atomic and structural data for Holmium provided on this page has been cross-referenced with primary chemical databases. For further primary-source research, consult the following global authorities:

    Bohr Models for All 118 Elements

    Toni Tuyishimire — Principal Software Engineer, Toni Tech Solution
    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.