We are asked about the difference between the atomic mass and mass of the nucleus of iron-56 (56Fe)
• Recall that the nucleus consists of protons and neutrons.
• A nucleon is either a proton or neutron. Thus, the mass of individual nucleons is the sum of the masses of protons and neutrons.
Mass of individual nucleons = Mass of protons + Mass of neutrons
Table Mass Defects and Binding Energies for Three Nuclei
|Nucleus||Mass of Nucleus (amu)||Mass of Individual Nucleons (amu)||Mass Defect (amu)||Binding Energy (J)||Binding Energy per Nucleon (J)|
|24 He||4.00150||4.03188||0.03038||4.53 10-12||1.13 10-12|
|2656 Fe||55.92068||56.44914||0.52846||7.90 10-11||1.41 10-12|
|92238 U||238.00031||239.93451||1.93420||2.89 10-10||1.21 10-12|
The atomic mass of iron-56 is 55.93494 amu.
Why is this number different from the mass of the nucleus given in the table above?
Frequently Asked Questions
What scientific concept do you need to know in order to solve this problem?
Our tutors have indicated that to solve this problem you will need to apply the Mass Defect concept. If you need more Mass Defect practice, you can also practice Mass Defect practice problems.