Formula: Mass Defect Mass of the nucleus    Neutron number    Proton number

Mass difference

Unit
The mass difference $$\class{brown}{\delta m}$$ of the individual nuclei components and the mass $$\class{brown}{m}$$ of the nucleus is not zero. This is called mass defect. This mass difference hides in the binding energy of the nucleus.

Mass of the nucleus

Unit
Mass of the nucleus formed by the union of $$N$$ neutrons and $$Z$$ protons. The nucleus is lighter than the sum of its components (mass defect).

Neutron number

Unit
Number of neutrons used to build a nucleus.

Proton number

Unit
Proton number (atomic number) is the number of protons used to build a nucleus.

Mass of a neutron

Unit
The rest mass of a neutron is: $$\class{brown}{m_{\text n}} ~=~ 1.674 \cdot 10^{−27} \, \mathrm{kg}$$

Mass of a proton

Unit
The rest mass of a proton is: $$\class{brown}{m_{\text p}} ~=~ 1.672 \cdot 10^{−27} \, \mathrm{kg}$$

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