The structure of the atom is what gives an element its chemical ... around the positive centre of the atom in circles called energy levels. Their mass is so small it is nearly zero.

it becomes a negatively-charged ion A helium atom has two electrons in an energy level outside the nucleus. The atom is neutral as it has two positive protons and two negative electrons.

Researchers are exploring multi-level atomic interactions to enhance quantum entanglement. Using metastable states in ...

The electronic structure of atoms and molecules is the series of energy levels that it are possible ... many of the defining characteristics of an atom or molecule, including their chemical ...