Ra
Interactive Shell Diagram

Radium Bohr Model, Electron Shell Diagram

Visualize the exact electron shell distribution of Radium (Ra). Its 88 total electrons orbit the microscopic nucleus across 7 quantum energy shells in the specific mathematical pattern 2 – 8 – 18 – 32 – 18 – 8 – 2.

Atomic Number: Z = 88Symbol: RaShells: 7Shell Pattern: 2-8-18-32-18-8-2Valence e⁻: 2

Live Bohr Shell Diagram

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

Radium Nuclear Composition

Protons, neutrons, and electrons at a glance

Protons

88

Positive charge carriers in the nucleus

Neutrons

138

Neutral mass carriers in the nucleus

Electrons

88

Across 7 shells: 2-8-18-32-18-8-2

Detailed Bohr Model Analysis

Radium's traditional Bohr model diagram provides a spectacular two-dimensional blueprint of its subatomic structure. By plotting its 88 negatively charged electrons rotating around a positively charged nucleus (containing 88 protons and approximately 138 neutrons), we can visually decrypt its chemical properties.

Across its 7 electron shells, Radium distributes its electrons in the following exact hierarchical sequence, from the innermost ring outward: 2 – 8 – 18 – 32 – 18 – 8 – 2.

Applying the Bohr Rules to Radium

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 Radium, 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 Radium, its 88 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 – 32 – 18 – 8 – 2 sequence. Because Radium 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 Radium's Valence Electrons

When analyzing the Bohr model of Radium, the absolute most critical ring is the outermost shell. This layer holds exactly 2 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 Radium has 2 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, Radium 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 Radium, represented universally by the chemical symbol Ra, holds the atomic number 88. This means that a standard neutral atom of Radium possesses exactly 88 protons within its dense nucleus, orbited precisely by 88 electrons. With a standard atomic weight of approximately 226.000 atomic mass units (u), Radium is classified fundamentally as a alkaline earth metal.

From a periodic standpoint, Radium resides in Period 7 and Group 2 of the periodic table, placing it firmly within the s-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, Radium exhibits a calculated atomic radius of 283 picometers (pm). When attempting to physically remove an electron from its outermost shell, it requires a primary ionization energy of 5.279 eV. Furthermore, its tendency to attract shared electrons in a covalent chemical bond—known as its electronegativity—measures at 0.9 on the Pauling scale. These specific subatomic metrics (radius, ionization, and electron affinity) combine to define exactly how Radium interacts, bonds, and reacts with every other chemical element in the observable universe.

Atomic Properties — Radium

Atomic Mass

226 u

Electronegativity

0.9 (Pauling)

Block / Group

S-block, Group 2

Period

Period 7

Atomic Radius

283 pm

Ionization Energy

5.279 eV

Electron Affinity

0.1 eV

Category

Alkaline Earth Metal

Oxidation States

+2

Real-World Applications

Ra-223 Bone Metastasis Therapy (Xofigo)Historical Luminous Watch DialsRadon Production (via Decay)Cancer Radiotherapy (Historical)Research Standard

Real-World Applications & Industrial Uses

The distinct electronic structure of Radium 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 Radium:

  • Ra-223 Bone Metastasis Therapy (Xofigo): Its baseline chemical reactivity makes it specifically suited for this primary role.
  • Historical Luminous Watch Dials: Used heavily in advanced manufacturing and chemical processing.
  • Radon Production (via Decay)
  • Cancer Radiotherapy (Historical)
  • Research Standard

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

  • Did You Know?

    Discovered by Marie and Pierre Curie in 1898. Radium glows blue-green in the dark due to radioluminescence. "Radium girls" painted watch dials with Ra-226 luminous paint in the 1920s, suffering devastating radiation poisoning. Ra-226 decays to radon gas. Ra-223 (Xofigo®) is an FDA-approved targeted alpha therapy for bone metastases from prostate cancer.

    Shell-by-Shell Capacity Table

    How each of Radium's 7 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)3232
    100%
    5O (n=5)1850
    36%
    6P (n=6)872
    11%
    7Q (n=7)298
    2%

    Shell Comparison: Radium vs Neighbors

    ← Previous Element

    Fr

    Francium

    Z=87

    2-8-18-32-18-8-1 shells

    View Bohr Model

    ⬤ Current

    Ra

    Radium

    Z=88

    2-8-18-32-18-8-2 shells

    Next Element →

    Ac

    Actinium

    Z=89

    2-8-18-32-18-9-2 shells

    View Bohr Model

    Frequently Asked Questions — Radium Bohr Model

    Authoritative References

    The atomic and structural data for Radium 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.