Nucleon - Definition, Nucleon Number, Binding Energy, Types, Properties, FAQs

We can define nucleon as a collective term for the subatomic particle that is either the proton or the neutron contained in the atomic nuclei. Protons are the positively charged subatomic particles and neutrons are the uncharged particles. The neutrons behave identically under the influence of the short range of the nuclear force. These subatomic particles are tightly bound in atomic nuclei and are scattered by each other. In this article, we will discuss what nucleons are, what nucleons are in physics, the binding energy per nucleon, the types of nucleons, and the properties of nucleons.

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What are Nucleons?

We can define nucleon as one of the particles of the atomic nucleus. Every atomic nucleus has one or more Nucleons in it. These Nucleons are surrounded by one or more electrons. They occupy a small space inside the nucleus. Every atom is made up of nucleons and can be further divided into smaller particles such as electrons, protons, and neutrons and they move around the nucleus. We can consider an atom like a mini solar system, where the electrons orbit a central star which is the nucleus and is composed of nucleons.

The strong interaction between these particles is independent of the electric charge. Also, we find that the unstable subatomic particles are heavier than nucleons. These are hyperons and baryon resonances. These comprise a nucleon among their final decay products. We can consider the nucleon as in the baryon ground state. Also, we know that every particle has its antiparticle. The antinucleons are of two types i.e. the antiproton and the antineutron.

What are Nucleons in Physics?

We study the Nucleons both in chemistry and in physics and a nucleon can be either a proton or a neutron. By finding the number of nucleons in a nucleus, we can easily find the mass number of the isotopes. We can consider Nucleons as composite particles made up of three quarks that are bonded together by a strong intermolecular force. This strong interaction between two or more nucleons is known as inter-nucleon interaction or nuclear force. We know this fact that protons and neutrons are the components of an atomic nucleus.

Binding Energy Per Nucleon

Even though the nucleus consists of neutrons and protons, we find that the mass of the nucleus is much less than the sum of the individual masses of the protons and neutrons. The difference is in the measurement of the binding energy per nucleon that keeps the nucleons together. This binding energy possessed by the nucleons can be determined by using the Einstein relationship:

Nuclear binding energy, $E=\Delta m \cdot c^2$

$\Delta m=0.0304 u$ for the alpha particles and gives a binding energy of 28.3 MeV.

Types of Nucleons

As we have already discussed, there are two types of nucleons i.e. protons and neutrons. A proton has a positive electric charge on it whereas; a neutron has no electric charge on it. These two particles are inside the nucleus of the atom and generate a positive charge as the neutron has no charge at all.

Proton

• Positively charged particles in the nucleus
• The charge of the proton is $+1 e$
• The mass of the proton is $1.007 \mathrm{ u}$
• It determines the atomic number of an element

Neutron

• The particle in the nucleus which has no charge
• The charge of the neutron is $0 \mathrm{e}$
• The mass of the neutron is approximately $1.008 \mathrm{u}$
• Reduces the electrostatic repulsion between the protons hence stabilising the nucleus.

Properties of Nucleons

• The neutron is not stable on its own. Generally, it can be found in nuclear reactions and is used in scientific analysis.
• Both the proton and neutron have three quarks. The proton contains two up quarks (which is the lightest of all quarks and is a major constituent of matter also a type of elementary particle) and one down quark (which is the second lightest of all quarks). On the contrary, a neutron contains one up quark and two down quarks.
• Nucleons are an integral part of the atomic nucleus as they cannot exist as independent nucleons.
• The nucleons are held with a strong force by the atomic nucleus. When this strong force gets broken, it produces a lot of power, and this power is known as nuclear energy which is similar to what is used in nuclear bombs.
• The Nucleons present in radioactive substances such as uranium can be very harmful as they can spread alpha radiation in a fraction of second.

Other properties are:

• Composition of Nucleus: Generally, the nucleus is composed of protons and neutrons and is collectively known as the nucleons.
• Nuclear charge: It is the total positive charge of the nucleus of an atom.

$$
\text { Nuclear Charge }=Z \cdot e
$$

• Nuclear mass: The nuclear mass is the total mass of protons and neutrons inside the nucleus.
• Nuclear Size and Shape: The shape of the nucleus is generally considered to be spherical and the size of the nucleus depends on the number of nucleons.

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