Molybdenum

Element 42 · Transition metal

Specimen

Atomic number: 42
Atomic mass: 95.95
State at room temperature: Solid
Melting point: 2,623 °C
Boiling point: 4,639 °C
Density: 10.2 g/cm³
Discovered: 1778

Physical data from PubChem.¹

Can I eat it?

In food and water: Your body needs it. Molybdenum, as molybdate in food, is a nutrient that some enzymes need. EFSA sets an adequate intake of 65 micrograms a day for adults. The RSC says larger amounts are toxic. ²³

The atom

Shell	Electrons
1 (K)	2
2 (L)	8
3 (M)	18
4 (N)	13
5 (O) outermost	1
Total	42

Configuration [Kr] 4d⁵ 5s¹

4d ↑ ↑ ↑ ↑ ↑

5s ↑

A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 42 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

Sources

1

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

Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.
2
European Food Safety Authority (EFSA), 2017. Dietary Reference Values for nutrients. Summary report , Section 4.5 (iodine) and 4.9 (molybdenum).
- Molybdenum is an essential component of certain enzymes ... An AI of 65 µg/day is proposed for adult men and women
3
Royal Society of Chemistry, 2026. Molybdenum - Element information, properties and uses .
- Although it is toxic in anything other than small quantities, molybdenum is an essential element for animals and plants.

Specimen

Can I eat it?

The atom

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Sources