Atomic Mass Calculator

Calculate atomic mass from proton and neutron counts. Displays results in atomic mass units (amu) and kilograms with instant calculations.

Atomic number - number of protons in the nucleus

Number of neutrons in the nucleus

Results

Atomic Mass

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Atomic Mass in Kilograms

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Mass Number (A)

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Frequently Asked Questions

What is atomic mass?

Atomic mass is the mass of an atom, including its protons, neutrons, and electrons. It's usually expressed in atomic mass units (u) or daltons (Da), where 1 u equals 1/12 the mass of a carbon-12 atom.

How do I find the atomic mass?

To calculate atomic mass, add the mass of protons and neutrons. Each proton and neutron has approximately 1 atomic mass unit, so atomic mass ≈ number of protons + number of neutrons.

What's the difference between atomic mass and mass number?

Mass number is the total count of protons and neutrons (always a whole number), while atomic mass is the actual mass measured in atomic mass units (can have decimal places due to binding energy effects).

Why do atoms need neutrons?

Neutrons help stabilize the atomic nucleus by providing the strong nuclear force without adding electrical charge. They prevent protons from repelling each other due to electromagnetic force.

What is an atomic mass unit (u)?

An atomic mass unit (u) is a unit of mass equal to 1/12 the mass of a carbon-12 atom. One u equals approximately 1.66 × 10⁻²⁷ kg.

What's the atomic mass of carbon-12?

Carbon-12 has an atomic mass of exactly 12.000000 u by definition, as it serves as the reference standard for atomic mass units. It has 6 protons and 6 neutrons.

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