From analogy we get further for the configuration of a possible negatively charged atom,
Comparing the outer ring of the atom considered with the ring of a helium atom, we see that the presence of the inner ring of two electrons in the beryllium atom markedly changes the properties of the outer ring; partly because the outer electrons in the configuration adopted for a neutral beryllium atom are more lightly bound than the electrons in a helium atom, and partly because the quantity
, which for helium is equal to
, for the outer ring in the configuration
is only equal to
