To determine the number of electrons in a human body, one must first consider the relation between mass and electrons.
As we all know, electrons have an extremely small mass - this makes it impractical to use their mass to determine the total number of electrons in a human body.
Consider that in most cases (a general state) every electron in a body will be in some way paired up with one proton. Next, consider that typically, for every proton there will be a neutron.
Now consider that the mass of 1 proton is one a.m.u. (atomic mass unit).
Let the mass of a person be 60.0kg (132lb). Their mass in grams is: 60'000g or 6.00x10^4 g
the mass of one proton is 1 amu = 1.6607x10^-24 g
Now consider the number of amu units within a human body of 60kg mass: mass / amu mass = #amu units
6.00x10^4g / 1.6607x10^-24g = 3.61x10^28
Now in the consideration that every proton will be paired with a neutron, we must divide the # of atomic mass units to derive the number of protons alone:
3.61x10^28 / 2 = 1.80x10^28 protons
it therefore stands to reason that there are approximately 1.80x10^28 electrons in the human body
