Antimony
Antimony (Sb, atomic number 51) is a Period 5 metalloid (p-block, 121.76 u). Rhombohedral metalloid that, like water, silicon, and bismuth, expands upon freezing. Used in flame-retardant formulations, lead-acid battery grids, and infrared semiconduct
Antimony is a chemical element on the periodic table with the atomic symbol Sb, atomic number 51, and standard atomic weight 121.76 u. Classified as a Metalloid within Group 15 and Period 5 (p-block), antimony possesses a ground-state electron configuration of [Kr] 4d10 5s2 5p3 distributed across 5 concentric Bohr electron shells (2 · 8 · 18 · 18 · 5) with 5 outer-shell electrons. Rhombohedral metalloid that, like water, silicon, and bismuth, expands upon freezing. Used in flame-retardant formulations, lead-acid battery grids, and infrared semiconductor detectors.
⚛️ Interactive Periodic Table Lab: Explore Antimony (Sb, Z = 51) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 18 · 5 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 Antimony?
Electron Shell Architecture and Ground-State Configuration
A neutral atom of antimony contains 51 protons in its atomic nucleus balanced by 51 electrons occupying quantized atomic orbitals. In the Bohr-Sommerfeld and quantum-mechanical orbital models, these electrons populate 5 principal energy shells (K (n=1): 2e−, L (n=2): 8e−, M (n=3): 18e−, N (n=4): 18e−, O (n=5): 5e−), terminating in the directional dumbbell-shaped p-orbital (azimuthal quantum number l = 1) with ground-state configuration [Kr] 4d10 5s2 5p3. Removing the most loosely bound valence electron from an isolated gaseous antimony atom requires a first ionization energy of 834 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 2.05.
Periodic Table Position and Neighboring Elements
Within the periodic table, Antimony occupies Period 5, Group 15 of the p-block (Metalloids). Along Period 5, it is flanked by Tin (Sn, Z = 50) and Tellurium (Te, Z = 52). Vertically within its periodic family, Antimony shares valence orbital symmetry and homologous chemical trends with Arsenic (As). Learners can interactively compare Antimony's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.
Physical and Thermodynamic Properties: How Does Antimony 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 antimony exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 903.78 K (+630.63 °C / +1167.1 °F) and transitions to the vapor phase at a normal boiling point of 1,908 K (+1634.85 °C / +2974.7 °F), spanning a liquid thermodynamic range of 1004.22 K. 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 Antimony'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 15 / Period 5 |
|---|---|---|---|
| Atomic Number & Symbol | Z = 51 (Sb) | 51 nuclear protons; nuclear charge +51e | Located in Period 5, Group 15 (p-block) |
| Standard Atomic Weight | 121.76 u (g/mol) | Abundance-weighted isotopic nucleon mass | ~71 neutrons in dominant/reference mass number |
| Electron Configuration | [Kr] 4d10 5s2 5p3 | Shells: 2 · 8 · 18 · 18 · 5 (5 outer-shell e−) | Metalloids valence orbital architecture |
| Electronegativity & Ionization | χ = 2.05; IE1 = 834 kJ/mol | Pauling bond polarity scale & first valence ionization enthalpy | Governs covalent vs. ionic bond character |
| Melting & Boiling Points | MP: 903.78 K; BP: 1908 K | Cohesive lattice energy and intermolecular forces | STP (298 K) phase: SOLID (Liquid range: 1004.22 K) |
| Principal Oxidation States | +3, +5, -3 | Valence electron donation, sharing, or acceptance | Discovered / First Isolated: Ancient |
Chemical Reactivity, Bonding, and Oxidation States: How Does Antimony Form Compounds?
Characteristic Oxidation States and Coordination Chemistry
As a p-block metalloid straddling the amphoteric staircase between metals and nonmetals, it exhibits intermediate ionization energy and electronegativity, forming directional covalent networks with semiconducting electronic bandgaps. In chemical compounds, antimony exhibits characteristic oxidation states of +3, +5, -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)—antimony 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 Ancient, Antimony carries a distinct cosmological and geochemical signature. With atomic number Z = 51 beyond the iron-56 binding-energy peak, antimony is synthesized astrophysically via neutron-capture nucleosynthesis—combining slow neutron capture (the s-process in asymptotic giant branch stars) and rapid neutron capture (the r-process in neutron-star mergers and core-collapse supernovae).
Biological Role and Scientific Applications: Why Is Antimony Important in Nature and Technology?
Biochemical Classification: Abiotic / Technological / Synthetic
In comparative biochemistry and systems physiology, Antimony 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
Rhombohedral metalloid that, like water, silicon, and bismuth, expands upon freezing. Used in flame-retardant formulations, lead-acid battery grids, and infrared semiconductor detectors. Researchers and students can further investigate Antimony'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 Antimony (Sb)?
Antimony (atomic number Z = 51) has the ground-state electron configuration [Kr] 4d10 5s2 5p3, distributing its 51 electrons across 5 shells as 2 · 8 · 18 · 18 · 5. Its outermost shell contains 5 electrons, placing Antimony in Group 15, Period 5 (p-block) as a member of the Metalloids. You can watch these 51 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.
What phase of matter is Antimony at room temperature, and when does it melt or boil?
At standard room temperature (298 K / 25 °C) and 1 atm pressure, Antimony is a crystalline solid. It melts at 903.78 K (+630.63 °C / +1167.1 °F) and boils at 1,908 K (+1634.85 °C / +2974.7 °F). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Antimony's exact solid, liquid, and gas transitions relative to all other elements.
How does Antimony function in biochemistry, materials science, and technology?
Rhombohedral metalloid that, like water, silicon, and bismuth, expands upon freezing. Used in flame-retardant formulations, lead-acid battery grids, and infrared semiconductor detectors. In biological systems, it is categorized under Abiotic / Technological / Synthetic, with principal oxidation states of +3, +5, -3 and a first ionization energy of 834 kJ/mol.