What is the atomic number of chromium?

The atomic number of chromium is 24. Its chemical symbol is Cr, and the number means that every chromium atom has 24 protons in its nucleus. An electrically neutral chromium atom also has 24 electrons, although it can gain or lose electrons to form ions.

Chromium is a hard, lustrous, steel-gray transition metal and the first element in Group 6 of the periodic table. Its name comes from the Greek word chroma, meaning “color,” because many chromium compounds are brightly colored. French chemist Louis Nicolas Vauquelin discovered the element in 1797, although metallic chromium was isolated a few years later.

Chromium is especially important in stainless steel, where it helps create a thin protective oxide layer that resists corrosion. It is also used in chrome plating and pigments. A common mix-up is confusing chromium’s atomic number, 24, with its relative atomic mass, which is about 52; atomic number counts protons, while atomic mass reflects the combined mass of protons and neutrons.