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. A helium atom that has lost or gained an ...

It is not the same as a helium atom as it does not contain any electrons but it is written with the same chemical nomenclature as a helium atom: \(_{2}^{4}\textrm{He}\) When a radioactive atom ...