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Hafnium

Element 72 · Transition metal

Specimen

Atomic number
72
Atomic mass
178.49
State at room temperature
Solid
Melting point
2,233 °C
Boiling point
4,603 °C
Density
13.3 g/cm³
Discovered
1923

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

Can I eat it?

In food and water
Not needed, little harm known. Hafnium has no known function in the body. The RSC lists it as low in toxicity. There are few studies of hafnium in food or water. 3

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The atom

Hf
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32
5 (O) 10
6 (P) outermost 2
Total72

Configuration [Xe] 4f¹⁴ 5d² 6s²

4f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
5d ↑ ↑
6s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 72 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 Xe core, with one arrow per electron.

Related elements

Group 4
Ti Titanium Zr Zirconium Rf Rutherfordium

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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

    Royal Society of Chemistry, 2026. Hafnium - Element information, properties and uses .

    • Hafnium has no known biological role, and it has low toxicity.
  4. 4

    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.