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Nucleon refers to either of the two subatomic particles, Proton and Neutron, which are components of the atomic nuclei. The number of nucleons in a nucleus indicates the weight of an isotope. Nucleons are composite particles formed from three quarks bound by a strong interaction. The interaction between two or more nucleons is known as inter nucleon interaction or nuclear force.
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Keyterms: Nucleon,Proton, Nucleon Number, Nuclear force, Binding energy
What is Nucleon?
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Nucleon refers to those subatomic particles (Proton and Neutron) present in the nucleus of an atom. Nucleons are surrounded by Electrons and occupy a very small space in the nucleus.
Simply put, the atom is like a mini solar system, with electrons orbiting the central, nucleonic star. Atoms can be divided into nucleons, which can be further divided into protons, neutrons and electrons orbiting the nucleus.
Nuclei Class 12 Important Notes PDF
Nuclei Class 12 Important Notes
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| Related Articles | ||
|---|---|---|
| Atoms and Nuclei Important Questions | Mass-Energy and Nuclear Binding Energy | Radioactive Decay Formula |
| Radioactivity | Beta Decay | Electron Mass |
Properties of Nucleon
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Neutrons are not independently stable; but have applications in nuclear processes and scientific research. Protons and Neutrons are made up of three quarks each.
Protons consist of two up quarks and one down quark while neutrons consist of one up quark and two down quarks.
Note: Quarks are a type of elementary particle and a chief constituent of matter. Up quarks are the lightest while down quarks are the second lightest.
Nucleons are held to the atomic nucleus with a strong force. This force, when broken, releases a huge amount of power in the form of nuclear energy similar to that of nuclear weapons. Nucleons can be hazardous when released from substances causing radioactive decay such as uranium. Such decayed nucleons can release alpha radiation within mere moments.
Types of Nucleons
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There are two main types of nucleons. They are:
- Protons: A proton is charged positively.
- Neutrons: A neutron is charged neutrally. This means it is not charged.
Both of these particles lie in the nucleus of the atom. One provides a positive charge, while the neutron does not have any charge.
Nucleon Diagram
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This is the diagram of a nucleon. The positively charged ones (the red ones) are Protons, the ones without a symbol (the green ones) do not have a charge and are neurons, and the ones which are negatively charged (the blue ones) are known as Electrons.
Attributes of Nucleon
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There are four major attributes in relation to Nucleons: Composition, Size and Shape, Load/Mass and Charge
- Composition: The nucleus consists of protons and neutrons collectively termed as nucleons.
- Nuclear Mass: The mass of the nucleus.
- Nuclear Charge: Number of protons and neutrons present in the nucleus.
- Nuclear Size and Shape: The nucleus is almost spherical in its shape and is minuscule in size.
Binding Energy Per Nucleon
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Though a nucleus is composed of protons and electrons, the nuclear mass will be lower than the sum of individual mass of protons and neutrons. The difference in masses can be calculated from the measurement of binding energy per nucleon. Using Einstein’s equation, Binding energy can be calculated as:
Nuclear binding energy = Δmc2
Where,
Δm is the mass of a nucleon
c is the speed of light, ie, 3.8 x 108 m/s
Since Δm for alpha particles is 0.0304 u (unit), this gives the binding energy of a nucleon as 28.3 MeV.
Note: Only known atomic nuclei components so far are protons and neutrons. These two particles can be found without the bigger nucleus itself.
Nucleon: Formula
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There are multiple formulas for multiple test calculations related to a nucleon. The below table has the name of the test, the formula as well as the PDG (Particle Data Group) results one gets when using that particular formula.
| Test | Formula | PDG Result |
|---|---|---|
| Mass | \(\frac{|m_p - m_p^-|}{m_p}\) | <2×10−9 |
| Change To Mass Ratio | \(\frac{|\frac{q_p^-}{m_p^-}|}{(\frac{q_p}{m_p})}\) | 0.99999999991(9) |
| Change to mass to mass ratio | \(\frac{|\frac{q_p^-}{m_p^-}| - \frac{q_p}{m_p}}{\frac{q_p}{m_p}}\) | (−9±9)×10−11 |
| Charge | \(\frac{|q_p + q_p^-|}{e}\) | <2×10−9 |
| Electron Charge | \(\frac{|q_p + q_p|}{e}\) | <1×10−21 |
| Magnetic Moment | \(\frac{| \mu_p + \mu_p^-|}{\mu_p}\) | (−0.1±2.1)×10−3 |
Things To Remember
- Nucleons are subatomic particles consisting of Protons and Neutrons present in the nucleus of an atom.
- Electrons rotate around the nucleus, which means that they are not regarded as nucleons.
- Quarks are a type of elementary particle and a chief constituent of matter.
- Nuclear force, when broken, releases nuclear energy similar to that of nuclear weapons.
- Under the influence of the short-range nuclear forces, protons (positively charged) and neutrons (unloaded), act equally.Both are bound into nuclei as they are dispersed.
- Nucleon, the proton and neutron constitute the atomic nuclei.
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Sample Questions
Ques. Nucleons are divided into: (2 marks)
(a) Electrons
(b) Protons
(c) Neutrons
(d) All of the above
Ans. All of the above
Explanation: According to the diagram of the nucleon, the positively charged ones (the red ones) are Protons, the ones without a symbol (the green ones) do not have a charge and are neurons, and the ones which are negatively charged (the blue ones) are known as Electrons.
Ques. The formula for nuclear binding energy is: (2 marks)
(a) Δmc²
(b) Δmc
(c) Δm+c2
(d) Δmc4
Ans. Δmc²
Explanation: Nuclear binding energy = Δmc²
Here,
Δm is the mass of a nucleon
c is the speed of light, which is, 3.8 x 108 m/s
Ques. Which Of the following statements is true? (2 marks)
(a) Every atom is made up of Nucleons
(b) Every atom is not made up of nucleons
(c) Every atom is independent of nucleons
(d) None of the above
Ans. Every atom is made up of Nucleons
Explanation: An atom consists of a positively charged nucleus, and it is surrounded by an electric field and a cloud of negative electrons.
Ques. Which Of the following statements is true? (2 marks)
(a) the mass of the nucleus is more than the sum of individual masses of the protons and neutrons
(b) the mass of the nucleus is less than the sum of individual masses of the protons and neutrons
(c) the mass of the nucleus is less than mass of the protons
(d) the mass of the nucleus is not dependent on masses of the protons and neutrons
Ans. The mass of the nucleus is less than the sum of individual masses of the protons and neutrons.
Explanation: The protons and neutrons approach nearer at a distance of 10-14 m during the creation of a nucleus. At the price of their masses, the energy necessary for that is expended by the nucleons. The weight of the nucleus discovered is therefore smaller than the total of the many nucleons.
Ques. What happens when an atomic nucleus is broken? (2 marks)
(a) A lot of energy is produced
(b) Less energy is produced
(c) No Energy is produced
(d) None of the above
Ans. A lot of energy is produced
Explanation: Fission happens when a neutron impacts the isotope nucleus, divides the nucleus into fragments and frees up a huge quantity of energy.
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