Atomic Mass Calculator
Calculate atomic mass and explore nuclear binding energy
Atomic mass is the total mass of an atom, including all its subatomic particles:
- Protons: Mass ≈ 1.007276466879 amu
- Neutrons: Mass ≈ 1.008664915823 amu
- Electrons: Mass ≈ 0.000548579909070 amu
The atomic mass unit (amu) is defined as 1/12 of the mass of a carbon-12 atom.
The mass defect is the difference between the sum of the masses of an atom's components and its actual mass:
- Mass defect occurs because some mass is converted to binding energy
- This follows Einstein's E = mc² equation
- The binding energy represents the strength of nuclear forces
- Enter the number of protons in the atom
- Enter the number of neutrons
- Enter the number of electrons
- Click Calculate to see:
- Total atomic mass in amu
- Mass defect
- Nuclear binding energy in MeV
Why is the actual atomic mass less than the sum of its parts?
This is due to mass defect - some mass is converted to binding energy that holds the nucleus together, following Einstein's E = mc² equation.
What is binding energy?
Binding energy is the energy required to break apart an atomic nucleus into its constituent protons and neutrons. It represents the strength of the nuclear force holding the nucleus together.
Why do we use atomic mass units (amu)?
The atomic mass unit (amu) is a convenient scale for atomic-level masses. It is defined as 1/12 of the mass of a carbon-12 atom, making it easier to work with than extremely small SI units.