Question

For each nuclide, use the masses of the proton and neutron to calculate the expected mass, and the difference between the measured and expected masses.

Answer 1

To determine the expected mass of a nuclide, sum the masses of protons, neutrons, and electrons. Compare it to the measured atomic mass to find the mass defect. This discrepancy represents the nuclear binding energy that holds the nucleus together.

Step-by-step explanation:

To calculate the expected mass of a nuclide such as 56Fe, sum the masses of its individual components: protons, neutrons, and electrons. We then compare this expected mass to the experimentally measured mass of the atom, which accounts for the nuclear binding energy. The mass of the individual nucleons (protons and neutrons) and the electrons is found in tables, such as those in relevant textbooks or scientific literature.

1. Multiply the mass of one proton, one neutron, and one electron by the number of each present in the nuclide.
2. Calculate the expected mass by adding together the masses of all those nucleons and electrons.
3. Determine the mass defect by subtracting the measured atomic mass from the expected mass.
4. To find the nuclear binding energy, multiply the mass defect by the energy equivalent per unit mass which is commonly given in electronvolts (eV).

For our example with 56Fe, which has 26 protons and 30 neutrons, the sum-of-parts value would be the total mass of these components if they were free and not bound in a nucleus. The discrepancy between this sum and the actual measured atomic mass is a representation of the energy that holds the nucleus together, known as the nuclear binding energy.