The mass of a helium-4 atom is 6.64648310224 g, and each of its two electrons has a mass of 9.10939310228 g. What fraction of this atom’s mass is contributed by its nucleus?
fraction of mass = mass of nucleus/mass of atom
The Attempt at a Solution
I suppose I should calculate the mass of nucleus first. But I only have the mass of the electrons, no mass of neutron, also no density...