The atom is neutral as it has two positive protons and two negative electrons. A helium atom that has lost or gained an electron is an ion. The ion has two positive protons but one electron so it ...

This model is also unable to explain the spectrum of atoms other than hydrogen, for example, helium atom which possesses only two electrons. Further, Bohr’s theory was also unable to explain the ...

In this configuration every atom has on the average ... On the other hand, it is obvious that a model which is so far away from reality that it simplifies liquid helium to an ideal gas, cannot ...