Cobalt (Co)

Gives glass and paint a deep blue colour.

Cobalt facts

Symbol
Co
Atomic number
27
Atomic mass
58.933
Family
Transition metals
Period
4
Group
9

What does cobalt react with?

Cobalt makes a new substance with 10 other elements and chemicals in our lab:

  • Cobalt + BoronCobalt boride Co + B → CoB · Only in a very hot furnace · Try it
  • Cobalt + OxygenCobalt(II,III) oxide 3Co + 2O₂ → Co₃O₄ · When heated · Try it
  • Cobalt + FluorineCobalt(III) fluoride 2Co + 3F₂ → 2CoF₃ · At room temperature · Try it
  • Cobalt + SiliconCobalt silicide Co + 2Si → CoSi₂ · Only in a very hot furnace · Try it
  • Cobalt + PhosphorusCobalt phosphide Co + P → CoP · When heated · Try it
  • Cobalt + SulfurCobalt(II) sulfide Co + S → CoS · When heated · Try it
  • Cobalt + ChlorineCobalt(II) chloride Co + Cl₂ → CoCl₂ · When heated · Try it
  • Cobalt + BromineCobalt(II) bromide Co + Br₂ → CoBr₂ · When heated · Try it
  • Cobalt + IodineCobalt(II) iodide Co + I₂ → CoI₂ · When heated · Try it
  • Cobalt + Hydrochloric AcidCobalt(II) chloride + hydrogen gas Co + 2HCl → CoCl₂ + H₂ · At room temperature · Try it

It also blends into a mixture, like an alloy, with 73 other metals when melted together.

Nothing happens when it's simply mixed with 15 of the others. 21 pairings have never been tried, because not enough atoms have ever existed.