For example, a helium atom has an atomic mass of 4, but an atomic number (or positive charge) of 2. Since electrons have almost no mass, it seemed that something besides the protons in the nucleus ...

The relative mass of a nucleus is the number of protons ... it becomes a negatively-charged ion A helium atom has two electrons in an energy level outside the nucleus. The atom is neutral as ...

In the accompanying figure the specific heat (CV) of an ideal Bose-Einstein gas is represented as a function of T/T0 where With m∗=the mass of a He atom and ... X-point of helium resembles ...