How can you find the atomic mass of an isotope with twenty nine protons and electrons and thirty six neutrons?

Answer 1

Using a Bainbridge mass spectrograph.

First of all, in these cases, we must thoroughly understand the cute differences between mass of atom, Atomic Mass, atomic weight, mass number, calculated mass and real mass.

Mass number, simply, is the total number of protons and neutrons (common name nucleon for proton and neutron) present in the nucleus of the atom.

Mass of the atom is the total mass of the nucleus and the mass of all the electrons.

But atomic mass is the total mass of the constituents of the atom namely protons, neutrons in the nucleus.

We calculate the mass of the core by getting the total mass of all the nucleons present in it.

Here we use a convenient unit for measuring mass. That one is known as atomic mass unit (amu) which equals to 1.66 x 10-27kg.

But the beauty is that this calculated mass is not found when we measure the mass of the nucleus by experimental means. The famous instrument to determine the mass of core accurately is a Bainbridge Mass Spectrograph.

The measured mass is slightly less than the calculated mass.

This is termed the mass defect. The equivalent energy to this mass defect is termed the binding energy of the nucleus.

Actually binding energy is that energy which has already come out when the protons and neutrons come together to form the nucleus hence the mass defect is the mass lost as heat energy.

More over there are four isotopes of copper having different number of neutrons in the nucleus. 34,35,36,37. The first and third are normal isotopes (non radioactive) but second and fourth are radio active. The isotopic mass of the isotope you have mentioned is measured as 64.9277 amu.