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Antimony

Element 51 · Metalloid

Specimen

Atomic number
51
Atomic mass
121.76
State at room temperature
Solid
Melting point
630.6 °C
Boiling point
1,587 °C
Density
6.685 g/cm³
Discovered
Ancient

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Harmful. Food and water contain only traces of antimony. WHO sets a drinking-water guideline of 20 micrograms per liter. Large doses by mouth cause vomiting. 34

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The atom

Sb
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 18
5 (O) outermost 5
Total51

Configuration [Kr] 4d¹⁰ 5s² 5p³

4d ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
5s ↑ ↓
5p ↑ ↑ ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 51 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Kr core, with one arrow per electron.

Related elements

Group 15
N Nitrogen P Phosphorus As Arsenic Bi Bismuth Mc Moscovium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    World Health Organization, 2003. Guidelines for drinking-water quality, chemical fact sheets: Antimony .

    The fact sheet gives 2003 as its assessment date.

    • Guideline value ... 0.02 mg/l (20 µg/l)
  4. 4

    Agency for Toxic Substances and Disease Registry (ATSDR), 2020. ToxFAQs for Antimony .

    • The levels of antimony found in the environment are lower than levels known to cause health problems. ... Swallowing large doses of antimony can cause vomiting in people.
  5. 5

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.