Dhristi JEE 2022-24

What are Nucleons in Chemistry?

In both Chemistry and Physics, a nucleon can be either a proton or a neutron, Its role is considered as a component of an atomic nucleus. The number of nucleons in a nucleus describes the mass number of an isotope. 

 

They are also known to be composite particles that are made of three quarks bound together by a strong interaction. The strong interaction between two or more nucleons is called inter-nucleon interaction/nuclear force, which is also finally caused by the strong interaction. Also, before the discovery of quarks, the term "strong interaction" was referred to as just internucleon interactions.

What are Nucleons?

A nucleon is one of the subatomic particles of the nucleus of an atom. Each atomic nucleus can contain one or more Nucleons and these nucleons are surrounded by one or more electrons. 

 

Nucleons occupy a very small space within the nucleus. Each and every atom is made up of nucleons which are then divided into particles viz:  electrons, protons, and neutrons that orbit the nucleus. 

 

We can imagine an atom like a mini solar system with electrons orbiting a central star which is the atomic nucleus, made up of nucleons. We can see the image below:

 

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Nucleon Definition

Nucleon, is either of the subatomic particles, viz: the proton and the neutron, residing in the atomic nuclei. Protons are positively charged subatomic particles and neutrons are uncharged that behave identically under the influence of the short-range nuclear force, both in the way these subatomic particles are tightly bound in atomic nuclei and in the manner they are scattered by each other. 

 

This strong interaction between these particles is independent of electric charge. Unstable subatomic particles are heavier than nucleons that are hyperons and baryon resonances and they comprise a nucleon among their final decay products; the nucleon is, therefore, the baryon ground state. The antinucleons are of two types viz:  the antiproton and the antineutron.

Types of Nucleons

Primarily, there are two types of nucleons viz: protons and neutrons.  A proton carries a positive electric charge, and a neutron has a neutral electric charge, which means that it bears no electric charge on it. These two particles reside in the nucleus of the atom and generate a positive charge because the neutron has no charge at all.

 

We must note that protons and neutrons are the only best-known components of atomic nuclei so far.  These two particles can be found on their own not being part of the larger nucleus (residing inside it). 

Point to Remember

A particle viz: the proton is the nucleus of the hydrogen-1 atom on its own which is considered the most abundant isotope of hydrogen.

 

So, whatever particles that reside in the nucleus are nucleons; however, electrons revolve around the nucleus, so it is not considered nucleons. 

Binding Energy of a Nucleon

As we know, a nucleus consists of neutrons and protons; however,  the mass of the nucleus is less than the sum of individual masses of the proton and the neutron. The difference lies in the measurement of binding energy per nucleon that tightly holds nucleons. The binding energy can be determined by Einstein’s equation. The relationship is as follows:

 

Nuclear binding energy = ∆mc2

 

Here,

 

∆m = mass of a nucleon

 

c = speed of light, i.e., 3.8 x 108 m/s

Since Δm for alpha particles is 0.0304 u (unit), this gives us the binding energy of a nucleon as 28.3 MeV.

What is a Nucleon?

So far we have been studying that a neutron is not a stable particle residing in an atom, but it can be used in nuclear reactions and scientific analysis. Protons and neutrons consist of three quarks. The proton has two up quarks, which is the lightest of all quarks and a  major constituent/portion of matter and a type of elementary/fundamental particle and one down quark, which is the second lightest quark, while a neutron is composed of one up quark and two down quarks.

 

These up and down quarks composed of protons and neutrons are an integral part of the atomic nucleus because they cannot persist as independent nucleons. The atomic nucleus holds the nucleons with a strong force of attraction. However, when the force is broken, a lot of power is generated and that power is termed nuclear energy which is similar to what we use in the production of nuclear bombs.

 

One must be very careful and understand that nucleons present in radioactive decay substances such as Uranium can be harmful since they can spread alpha radiation in a fraction of seconds. 

All about Nucleon: Attributes

  • Composition of Nucleus: The nucleus is made up of protons and neutrons that are collectively called nucleons.

  • Nuclear charge: The nucleus comprises protons and neutrons.

  • Nuclear mass: We call the mass of the nucleus a nuclear mass. 

  • Nuclear Size and shape: The nucleus is considered nearly spherical in shape.

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FAQs (Frequently Asked Questions)

1. What are the Properties of the Nucleus?

Among the various properties of an atomic nucleus, some of the properties of a nucleus are mentioned below: 

  • The nucleus is composed of protons and neutrons which are residing inside it and are called nucleons. 

  • These nucleons are bounded by an energy called binding energy.

2. What are the Properties of Nuclear Force?

The properties of the nuclear force can be described from the properties of the structure an atom nucleus creates. The protons and neutrons maintain their size while residing inside a nucleus, which means that the nuclear force is both attractive and repulsive.

3. Does Nucleus Particles Have a Nuclear Spin and Angular Momentum. If yes, then How?

Yes, Nucleus particles do bear a nuclear spin and angular momentum.


Since protons and neutrons remain in continuous motion in a quantized orbit; this orbital motion produces the nucleon with mechanical angular momentum. Besides orbital motion, nucleons have internal angular momentum known as spin. As a result, they bear an angular momentum linked with an orbital spin.

4. What is the Difference Between a Nucleon and a Nucleus?

A nucleon is a subatomic particle of the atomic nucleus, which is either a proton or a neutron while the nucleus is the core, central part round that remains assembled.

5. Are neutrons the same as nucleons?

No, both are quite different. Nucleon is the subatomic part of the nucleus while neutron is the subatomic part forming part of the nucleus of an atom that has no charge.  

6. What are the types of nucleons?

There are two types of nucleons - protons and neutrons. Electrons are the subatomic particles that have a negative charge while protons are the subatomic particles having positive charge.  All protons are bound together in any nucleus on account of a strong nuclear force. 

7. What is the binding energy of a nucleon?

The binding energy is the amount of energy required to separate a particle from a system of particles.  It is more applicable to the subatomic particles of atomic nuclei. Nuclear binding energy separates an atomic nucleus into its protons and neutrons.

8. What is the nuclear mass of nucleons?

The mass defect can be calculated using equation Δm = (Z(mp + me) + (A – Z)mn) – matom, where: Δm = mass defect (atomic mass unit (amu)); mp = mass of a proton (1.007277 amu); mn = mass of a neutron (1.008665 amu); me = mass of an electron (0.000548597 amu); matom = mass of nuclide X Z A (amu); Z = atomic number. 

9. Will questions come from types of nucleons?

Yes, questions can come from any part of the chapter. The chapter on nucleons is quite important and can be read by all students who wish to excel in the test that comes on it. Types of nucleons are also interesting as the students will find the concepts easy.  Students cannot afford to do selective studying in chemistry as questions can come from any section. To be on the safe side, they must read everything that’s a part of the chapter.  Many questions might come from types of nucleons.

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