Question

why mass of electron is neglected while computing atomic mass

Answer 1

Answer:

Electron mass is 1860 times less than proton mass so it is considered as insignificant and ignored in mass calculation. ... Mass of an electron is very less compared to the mass of protons and neutrons. Mass of a proton is nearly 1000 times the mass of electron. So their mass is neglected.

Answer 2

Answer:

elctrons are much smaller in mass than protons

therefore they don't contribute much to be an element over all atomic mass

hope its help you