Atomic Mass
Calculate the atomic mass of any isotope from protons and neutrons. Includes mass defect calculation, binding energy analysis, and isotope identification with natural abundance data.
Sample Examples
โ๏ธ Carbon-12 (Reference Standard)
The standard reference for atomic mass - exactly 12 amu by definition
Click to use
๐ง Deuterium (Heavy Hydrogen)
Hydrogen-2, used in nuclear fusion and heavy water production
Click to use
๐ฉ Iron-56 (Most Stable Nucleus)
Has the highest binding energy per nucleon - extremely stable
Click to use
โก Uranium-235 (Fissile)
Used in nuclear reactors and weapons - undergoes fission
Click to use
๐ Helium-4 (Alpha Particle)
Doubly magic nucleus, very stable - emitted in alpha decay
Click to use
๐ Carbon-14 (Dating Isotope)
Radioactive isotope used for radiocarbon dating of organic materials
Click to use
Enter Particle Counts
โ ๏ธFor educational and informational purposes only. Verify with a qualified professional.
What is Atomic Mass?
Atomic mass is the mass of an atom, including its protons, neutrons, and electrons. While electrons contribute negligibly to the total mass, protons and neutrons (collectively called nucleons) make up nearly all of an atom's mass. Atomic mass is typically expressed in atomic mass units (amu) or daltons (Da), where 1 amu equals 1/12 the mass of a carbon-12 atom.
Atomic Mass vs Mass Number
- Mass Number (A): Integer count of protons + neutrons
- Atomic Mass: Actual measured mass in amu (includes binding energy effects)
- Difference: Atomic mass is slightly less due to mass-energy conversion
Mass Defect & Binding Energy
- Mass Defect: The "missing" mass converted to energy
- Binding Energy: Energy holding the nucleus together
- E = mcยฒ: Mass-energy equivalence in action
How to Calculate Atomic Mass
The atomic mass formula provides a quick approximation, while precise values come from experimental measurements or semi-empirical mass formulas that account for nuclear binding energy.
- Enter the number of protons (Z): This determines the element identity
- Enter the number of neutrons (N): This determines the specific isotope
- Calculate mass number: A = Z + N
- Get atomic mass: Actual mass from database or calculated using nuclear physics models
- Analyze results: View binding energy, mass defect, and isotope properties
When to Use an Atomic Mass Calculator
Chemistry Studies
Understanding isotopes, calculating molar masses, and studying atomic structure in chemistry courses.
Nuclear Physics
Calculating binding energies, analyzing nuclear stability, and understanding radioactive decay.
Research Applications
Mass spectrometry data analysis, radioisotope studies, and nuclear energy calculations.
Atomic Mass Formulas
Mass Number
where: Z = protons, N = neutrons
Mass Defect
m_p = 1.007276 amu, m_n = 1.008665 amu
Binding Energy
1 amu = 931.5 MeV/cยฒ
Unit Conversion
1 amu = 1/12 mass of Carbon-12
๐ Official Data Sources
โ ๏ธ Disclaimer: This calculator uses IUPAC-recommended standard atomic weights. For precision work, consult the latest CIAAW tables.