Mass defect is the difference between the measured mass of a nucleus and the sum of the masses of its constituent nucleons.

Define binding energy .

Binding energy is the energy required to break a nucleus into its constituent protons and neutrons.

The formation of a nucleus from a system of isolated protons and neutrons releases energy, making it an .......... reaction.

The formation of a nucleus from a system of isolated protons and neutrons releases energy, making it an exothermic reaction.

True or False? Binding energy is energy stored within the nucleus.

False. Binding energy is the energy that must be put into the nucleus to pull it apart — it is not energy stored within the nucleus.

Give two real-world examples where mass-energy equivalence occurs.

The fusion of hydrogen into helium in the centre of the Sun The fission of uranium in nuclear power plants

Define the unified atomic mass unit (u).

The unified atomic mass unit is the mass of exactly one-twelfth of an atom of carbon-12.

What is 1 u equivalent to in MeV?

1 u is equivalent to 931.5 MeV .

One atom of carbon-12 has a mass of exactly .......... u.

One atom of carbon-12 has a mass of exactly 12 u.

Why is the actual mass of a nucleus, such as uranium-235, slightly lower than the value suggested by its nucleon number?

Due to mass-energy equivalence — some mass is converted to binding energy when the nucleus forms, so the true mass is lower than the sum of its nucleon masses.

True or False? The mass of an atom in a.m.u. is exactly equal to the sum of its protons and neutrons.

False. The mass in a.m.u. is only roughly equal to the nucleon number — the actual mass is slightly lower due to mass-energy equivalence.

Define binding energy per nucleon .

Binding energy per nucleon is the binding energy of a nucleus divided by the number of nucleons in the nucleus.

Which nuclide has the highest binding energy per nucleon, and what does this tell us?

Iron-56 has the highest binding energy per nucleon, making it the most stable of all nuclides.

Which three light nuclides do not fit the general low-A trend on the binding energy per nucleon graph?

Helium-4 — particularly stable, so has an unusually high binding energy per nucleon Carbon-12 — can be considered three helium nuclei bound together Oxygen-16 — can be considered four helium nuclei bound together

Why are nuclei with a high nucleon number, A, most likely to undergo fission?

Their binding energy per nucleon is relatively high but gradually decreasing with A, making them the least stable of the heavy nuclides.

When plotting the binding energy per nucleon graph, the curve should not begin at nucleon number A = .......... , since this is not a real nucleus.

When plotting the binding energy per nucleon graph, the curve should not begin at nucleon number A = 0 , since this is not a real nucleus.

True or False? A higher binding energy per nucleon means a nucleus is less stable.

False. A higher binding energy per nucleon means a nucleus is more stable, since more energy is needed to pull it apart.

Define nuclear fusion .

Nuclear fusion is the process in which small nuclides combine to make larger nuclei, releasing energy.

Explain why nuclei must have high kinetic energy in order to fuse.

Nuclei must get close enough for the short-range strong nuclear force to bind them, but first they must overcome the electrostatic repulsion between their (positively charged) protons.

Why can nuclear fusion only be achieved in an extremely hot, dense environment such as the core of a star?

Such conditions give nuclei enough kinetic energy to overcome electrostatic repulsion and get close enough for the strong nuclear force to bind them.

In the proton-proton chain, four hydrogen nuclei fuse to eventually produce one .......... nucleus, plus the release of energy.

In the proton-proton chain, four hydrogen nuclei fuse to eventually produce one helium-4 nucleus, plus the release of energy.

True or False? The mass of the nucleus produced by fusion is greater than the total mass of the original nuclei.

False. The mass of the new nucleus is less than the mass of the original constituent nuclei, since some mass is converted into energy .

International A Level (IAL)PhysicsEdexcelFlashcards5. Thermodynamics, Radiation, Oscillations & CosmologyNuclear Fusion & Fission

Nuclear Fusion & Fission (Edexcel International A Level (IAL) Physics): Flashcards

Exam code: YPH11

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FrontNuclear Binding Energy & Mass Deficit
Define mass defect.

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Cards in this collection (25)

Define mass defect.
Mass defect is the difference between the measured mass of a nucleus and the sum of the masses of its constituent nucleons.
Define binding energy.
Binding energy is the energy required to break a nucleus into its constituent protons and neutrons.
State the equation linking the energy released, $Δ E$ , to the mass defect, $Δ m$ .
$Δ E = Δ m c^{2}$
State the equation for the mass defect, $Δ m$ , of a nucleus.
$Δ m = Z m_{p} + (A - Z) m_{n} - m_{t o t a l}$
The formation of a nucleus from a system of isolated protons and neutrons releases energy, making it an .......... reaction.
The formation of a nucleus from a system of isolated protons and neutrons releases energy, making it an exothermic reaction.
True or False?
Binding energy is energy stored within the nucleus.
False.
Binding energy is the energy that must be put into the nucleus to pull it apart — it is not energy stored within the nucleus.
Give two real-world examples where mass-energy equivalence occurs.
- The fusion of hydrogen into helium in the centre of the Sun
- The fission of uranium in nuclear power plants
Define the unified atomic mass unit (u).
The unified atomic mass unit is the mass of exactly one-twelfth of an atom of carbon-12.
What is 1 u in kilograms?
$1 u = 1.66 \times 10^{- 27} kg$
What is 1 u equivalent to in MeV?
1 u is equivalent to 931.5 MeV.
One atom of carbon-12 has a mass of exactly .......... u.
One atom of carbon-12 has a mass of exactly 12 u.
Why is the actual mass of a nucleus, such as uranium-235, slightly lower than the value suggested by its nucleon number?
Due to mass-energy equivalence — some mass is converted to binding energy when the nucleus forms, so the true mass is lower than the sum of its nucleon masses.
True or False?
The mass of an atom in a.m.u. is exactly equal to the sum of its protons and neutrons.
False.
The mass in a.m.u. is only roughly equal to the nucleon number — the actual mass is slightly lower due to mass-energy equivalence.
Define binding energy per nucleon.
Binding energy per nucleon is the binding energy of a nucleus divided by the number of nucleons in the nucleus.
Which nuclide has the highest binding energy per nucleon, and what does this tell us?
Iron-56 has the highest binding energy per nucleon, making it the most stable of all nuclides.
Which three light nuclides do not fit the general low-A trend on the binding energy per nucleon graph?
- Helium-4 — particularly stable, so has an unusually high binding energy per nucleon
- Carbon-12 — can be considered three helium nuclei bound together
- Oxygen-16 — can be considered four helium nuclei bound together
Why are nuclei with a high nucleon number, A, most likely to undergo fission?
Their binding energy per nucleon is relatively high but gradually decreasing with A, making them the least stable of the heavy nuclides.
When plotting the binding energy per nucleon graph, the curve should not begin at nucleon number A = .........., since this is not a real nucleus.
When plotting the binding energy per nucleon graph, the curve should not begin at nucleon number A = 0, since this is not a real nucleus.
True or False?
A higher binding energy per nucleon means a nucleus is less stable.
False.
A higher binding energy per nucleon means a nucleus is more stable, since more energy is needed to pull it apart.
Define nuclear fusion.
Nuclear fusion is the process in which small nuclides combine to make larger nuclei, releasing energy.
What are the products of the deuterium-tritium fusion reaction?
${}_{1}^{2}H +_{1}^{3} H \to_{2}^{4} H e +_{0}^{1} n$
A helium nucleus and a neutron are produced, along with the release of energy.
Explain why nuclei must have high kinetic energy in order to fuse.
Nuclei must get close enough for the short-range strong nuclear force to bind them, but first they must overcome the electrostatic repulsion between their (positively charged) protons.
Why can nuclear fusion only be achieved in an extremely hot, dense environment such as the core of a star?
Such conditions give nuclei enough kinetic energy to overcome electrostatic repulsion and get close enough for the strong nuclear force to bind them.
In the proton-proton chain, four hydrogen nuclei fuse to eventually produce one .......... nucleus, plus the release of energy.
In the proton-proton chain, four hydrogen nuclei fuse to eventually produce one helium-4 nucleus, plus the release of energy.
True or False?
The mass of the nucleus produced by fusion is greater than the total mass of the original nuclei.
False.
The mass of the new nucleus is less than the mass of the original constituent nuclei, since some mass is converted into energy.

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