The members of the cube, however, are closer to the 8 chromium atoms in the unit cell that are not part of either polyhedron.

Ruby is an aluminum oxide crystal in which some of the aluminum atoms have been replaced with chromium atoms.

The green and blue wavelengths in the flash excited electrons in the chromium atoms to a higher energy level.

Commonly three electrons are added to a chromium atom, reducing it to oxidation state +3.

Firstly, the molecule can spin with the hydrogen atom seeming to orbit the chromium atom.

Thirdly, electrons can change from one atomic orbital to another in the chromium atom.

These natural ones contain more chromium atoms.

Sometimes some of the aluminium atoms get replaced with chromium atoms.

Its chromium atoms have oxidation state (+6).

The solid consists of chains of tetrahedrally coordinated chromium atoms that share vertices.