Nobelium
Nobelium (No, atomic number 102) is a Period 7 actinide (f-block, 259 u). Because its 5f¹⁴ subshell is completely filled, Nobelium uniquely favors the +2 oxidation state (No²⁺) in aqueous solution over the +3 state typical of other actinides.
Nobelium is a chemical element on the periodic table with the atomic symbol No, atomic number 102, and standard atomic weight 259 u. Classified as a Actinide within Group 3 and Period 7 (f-block), nobelium possesses a ground-state electron configuration of [Rn] 5f14 7s2 distributed across 7 concentric Bohr electron shells (2 · 8 · 18 · 32 · 32 · 8 · 2) with 2 outer-shell electrons. Because its 5f¹⁴ subshell is completely filled, Nobelium uniquely favors the +2 oxidation state (No²⁺) in aqueous solution over the +3 state typical of other actinides.
⚛️ Interactive Periodic Table Lab: Explore Nobelium (No, Z = 102) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 32 · 32 · 8 · 2 electron shells, simulate live phase transitions from 0 K to 6,000 K, and compare periodic heatmaps across all 118 IUPAC elements.
Atomic Structure and Periodic Trends: How Do Quantum Orbitals Define Nobelium?
Electron Shell Architecture and Ground-State Configuration
A neutral atom of nobelium contains 102 protons in its atomic nucleus balanced by 102 electrons occupying quantized atomic orbitals. In the Bohr-Sommerfeld and quantum-mechanical orbital models, these electrons populate 7 principal energy shells (K (n=1): 2e−, L (n=2): 8e−, M (n=3): 18e−, N (n=4): 32e−, O (n=5): 32e−, P (n=6): 8e−, Q (n=7): 2e−), terminating in the seven-orbital f-subshell manifold (azimuthal quantum number l = 3) with ground-state configuration [Rn] 5f14 7s2. Removing the most loosely bound valence electron from an isolated gaseous nobelium atom requires a first ionization energy of 642 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 1.30.
Periodic Table Position and Neighboring Elements
Within the periodic table, Nobelium occupies Period 7, Group 3 of the f-block (Actinides). Along Period 7, it is flanked by Mendelevium (Md, Z = 101) and Lawrencium (Lr, Z = 103). Vertically within its periodic family, Nobelium shares valence orbital symmetry and homologous chemical trends with Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U). Learners can interactively compare Nobelium's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.
Physical and Thermodynamic Properties: How Does Nobelium Behave Across Temperature Regimes?
Standard Phase, Melting Point, and Boiling Point Dynamics
At standard ambient temperature and pressure (298.15 K / 25 °C, 1 atm), elemental nobelium exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 1,100 K (+826.85 °C / +1520.3 °F) and transitions to the vapor phase at a normal boiling point of Unknown (predicted synthetic regime), spanning a liquid thermodynamic range of N/A (sublimes or synthetic regime). In the CRV Science Dynamic Periodic Table, dragging the live temperature slider between absolute zero (0 K) and solar-photosphere temperatures (6,000 K) dynamically tracks Nobelium's state transitions in real time alongside enthalpy and entropy phase equilibria.
Quantitative Atomic and Thermodynamic Parameter Matrix
| Parameter | Quantitative Value / Formula | Physical / Quantum Basis | Comparative Context in Group 3 / Period 7 |
|---|---|---|---|
| Atomic Number & Symbol | Z = 102 (No) | 102 nuclear protons; nuclear charge +102e | Located in Period 7, Group 3 (f-block) |
| Standard Atomic Weight | 259 u (g/mol) | Abundance-weighted isotopic nucleon mass | ~157 neutrons in dominant/reference mass number |
| Electron Configuration | [Rn] 5f14 7s2 | Shells: 2 · 8 · 18 · 32 · 32 · 8 · 2 (2 outer-shell e−) | Actinides valence orbital architecture |
| Electronegativity & Ionization | χ = 1.30; IE1 = 642 kJ/mol | Pauling bond polarity scale & first valence ionization enthalpy | Governs covalent vs. ionic bond character |
| Melting & Boiling Points | MP: 1100 K; BP: Unknown | Cohesive lattice energy and intermolecular forces | STP (298 K) phase: SOLID (Liquid range: N/A (sublimes or synthetic regime)) |
| Principal Oxidation States | +2, +3 | Valence electron donation, sharing, or acceptance | Discovered / First Isolated: 1966 |
Chemical Reactivity, Bonding, and Oxidation States: How Does Nobelium Form Compounds?
Characteristic Oxidation States and Coordination Chemistry
As a 5f-block actinide element with radially extended 5f, 6d, and 7s valence orbitals and an unstable heavy nucleus, it combines multi-valent actinide coordination chemistry with radioactive alpha, beta, or spontaneous-fission decay. In chemical compounds, nobelium exhibits characteristic oxidation states of +2, +3. Depending on the electronegativity difference (Δχ) of its bonding partners—such as Oxygen (χ = 3.44), Fluorine (χ = 3.98), Chlorine (χ = 3.16), Nitrogen (χ = 3.04), Carbon (χ = 2.55), or Hydrogen (χ = 2.20)—nobelium forms redox-specific oxides, halides, hydrides, or coordination complexes governed by Gibbs free energy (ΔG = ΔH − TΔS).
Nucleosynthesis, Discovery History, and Elemental Origins
First identified or isolated in 1966, Nobelium carries a distinct cosmological and geochemical signature. As a synthetic transuranic element (Z = 102), nobelium does not persist in primordial terrestrial minerals and is produced atom-by-atom in nuclear reactors or heavy-ion particle accelerators.
Biological Role and Scientific Applications: Why Is Nobelium Important in Nature and Technology?
Biochemical Classification: Abiotic / Technological / Synthetic
In comparative biochemistry and systems physiology, Nobelium is classified as Abiotic / Technological / Synthetic. No known essential biological role; important in planetary geochemistry, astrophysics, materials science, or nuclear physics. Across terrestrial and marine ecosystems, its chemical speciation interacts with thermodynamics, enthalpy, entropy, chemistry.
Key Mechanistic Functions and Technological Uses
Because its 5f¹⁴ subshell is completely filled, Nobelium uniquely favors the +2 oxidation state (No²⁺) in aqueous solution over the +3 state typical of other actinides. Researchers and students can further investigate Nobelium's functional role alongside all 118 elements by launching the Interactive Periodic Table & Element Detective Lab on CRV Science Learn.
Frequently Asked Scientific Questions
What is the electron configuration and valence shell structure of Nobelium (No)?
Nobelium (atomic number Z = 102) has the ground-state electron configuration [Rn] 5f14 7s2, distributing its 102 electrons across 7 shells as 2 · 8 · 18 · 32 · 32 · 8 · 2. Its outermost shell contains 2 electrons, placing Nobelium in Group 3, Period 7 (f-block) as a member of the Actinides. You can watch these 102 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.
What phase of matter is Nobelium at room temperature, and when does it melt or boil?
At standard room temperature (298 K / 25 °C) and 1 atm pressure, Nobelium is a crystalline solid. It melts at 1,100 K (+826.85 °C / +1520.3 °F) and boils at Unknown (predicted synthetic regime). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Nobelium's exact solid, liquid, and gas transitions relative to all other elements.
How does Nobelium function in biochemistry, materials science, and technology?
Because its 5f¹⁴ subshell is completely filled, Nobelium uniquely favors the +2 oxidation state (No²⁺) in aqueous solution over the +3 state typical of other actinides. In biological systems, it is categorized under Abiotic / Technological / Synthetic, with principal oxidation states of +2, +3 and a first ionization energy of 642 kJ/mol.