Alpha Particle Mass

Edited By Vishal kumar | Updated on Jul 02, 2025 04:58 PM IST

We get alpha particles generally when there is radioactive decay. Also, the alpha particles are known to possess an average kinetic energy of 5MeV and velocity in the vicinity of 5% of the speed of light. We also get alpha particles in high-energy particle accelerators. They are considered to be highly ionized particles and have very low penetration depth.

This Story also Contains

What is an Alpha Particle?
Alpha Particle Mass
Fundamental Properties of Alpha Particles
Uses of Alpha Radiations

Here in this article, we will discuss what is an alpha particle, the alpha particle mass in amu, the alpha particle symbol, the alpha particle mass compared to proton, the speed of the alpha particle, what is the value of alpha, the mass of proton deuteron and alpha particle mass and charge.

What is an Alpha Particle?

We know that the Alpha particles are the particles that consist of two protons and two neutrons. The protons and the neutrons are tightly bound together with each other. Basically, they are emitted from the nucleus of some radionuclides during radioactive decay which is known as alpha-decay. An alpha-particle is similar to the nucleus of a normal helium atom that has four as its atomic mass. Alpha particles are also known as alpha radiation or alpha rays.

Alpha particle digrame

The alpha particle mass and charge are 6.644657230 × 10^-27 Kg and +2 respectively.

Now, let us discuss the Characteristics of Alpha Particle

Parameter	Value
Charge of alpha particle	2
Spin	0
Alpha Particle Mass
Mass of alpha particle in GeV/c²	3.727379378(23) GeV/c²
Alpha particle mass kg	6.644657230(82) х 10⁻²⁷kg
Alpha particle mass in amu	4.001506179127(63) u
Composition	Two Protons Two Neutrons
Activeness	Highly active & energetic
Penetration Power	Low
Ionization Power	Highest
Speed	In the order of 10⁷ m/s.
Mass of alpha particle in eV	3.727379378(23) GeV/c2
Alpha particle mass number	4
Alpha particle charge	Positive
Alpha particle symbol	α, & alpha2+, He2+.
Alpha particle mass compared to proton	Mass of alpha particle = 4 × mass of a proton

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Fundamental Properties of Alpha Particles

Alpha particles are the carriers of double positive charge of that of the proton, i.e., equal to the charge on the Helium nucleus.
The mass of an α-particle is four times the mass of a Hydrogen atom, i.e., it is equivalent to the mass of the Helium atom.
Generally, we find the range of the velocity of alpha particles in between 1.4 х 10⁷ m/s to 2.1 х 10⁷ m/s, depending on the source emitting/radiating it.
Due to the large mass of alpha particles, the penetrating power of these particles is comparatively lesser. It is about 1/10³ times the penetrating power of beta rays and 1/10⁵ times that of the gamma rays.
In spite of having a large size and low perforating power, alpha radiation can be stopped by a 0.02 cm thick aluminum sheet.
When alpha particles are stopped, they give rise to heating effects. In spite of the alpha particles having very low perforating power, they can easily cause burns on the human body.
Because of their large mass and high-stepping speed, these particles have excessive ionizing efficiency. It means that due to a single alpha particle, thousands of ions can be brought forth before being absorbed.
The distance that an alpha particle travels in the air depends on the radioactive source producing it. Generally, at the normal pressure in air, we can find the range of alpha particles deviating from 3 to 8 cm.
Alpha particles also produce fluorescence in some of the substances, like Barium-Platinocyanide and zinc sulfide (ZnS).
Alpha particles affect the photographic plates fractionally.
Alpha particles can be deflected both by electric & magnetic fields at smaller angles.
Alpha particles can be garbled while passing through thin metal foils.
Alpha particle mass compared to proton: The mass of alpha particle is about four times that of proton.

Most of the Alpha particles were disordered at very small angles. However, it has been found that a few of them got deflected at an angle greater than the right angle.

Related Topics,

Uses of Alpha Radiations

Some of the uses of Alpha Radiations are:

For the Treatment of Cancer Patients

We use alpha particles in the treatment of cancer patients. While treating cancer patients, the Doctors use a technique known as the Unsealed Source Radiotherapy. In this technique, alpha particles like Radium-226 are inserted in tiny amounts into the cancerous masses. Generally, we use Radium-223 to treat bone cancer.

Static Eliminator

We know that a static eliminator is a common technique that is used in industries like paper mills. With the help of this technique, we can eliminate static electricity in industries. The alpha particles attract free electrons towards themselves and as a result, the potential of the static electricity is reduced.

Pacemaker Battery

We can increase the life of a battery by using alpha radiations as the source of energy in pacemakers. Alpha radiation of Plutonium-238 is considered as the best fuel source for heart pacemakers.

Oil Industries

Alpha particles are considered to be the best source of energy generally in remote areas. Alpha radiation of Strontium-90 is considered the best source to increase the lifespan of batteries.

Smoke Detectors

Smoke detectors are of two types

Photoelectric smoke detector
Ionization smoke chamber detector.

Ionization smoke chamber detectors are commonly found in household items that keep us safe by alerting smoke in our homes. A small amount of isotope of Americium, i.e., Americium-241 is used in these detectors as the source of alpha particles.

These alpha radiations ionize the air molecules and allow a very small amount of current to flow between the electrodes. Due to this current the alarm rings.

In short, An alpha particle consists of two protons and two neutrons. The mass of an alpha particle is approx 4 amu. Understanding the mass of alpha particles is helpful in fields like nuclear physics and radiation therapy.

Frequently Asked Questions (FAQs)

1. What is an alpha particle?

We know Alpha particles as the particles that consists of two protons and two neutrons. The protons and the neutrons are tightly bound together with each other.

2. What is an alpha particle?

An alpha particle is a positively charged particle consisting of two protons and two neutrons, identical to the nucleus of a helium-4 atom. It is emitted by some radioactive nuclei during alpha decay.

3. What is the charge on alpha particles?

The charge on the alpha particle is positive.

4. What is the mass of an alpha particle?

The mass Of an Alpha Particle is 6.644657230 × 10-27 Kg.

5. What does an alpha particle contain?

An alpha particle contains two protons and two neutrons.

6. What is the symbol of the alpha particle?

The symbol of the alpha particle is α.

7. How does the mass of an alpha particle compare to that of a proton?

An alpha particle has approximately four times the mass of a proton. This is because an alpha particle contains two protons and two neutrons, while a proton is a single particle.

8. What is the charge-to-mass ratio of an alpha particle?

The charge-to-mass ratio of an alpha particle is lower than that of a proton or electron. This is because while an alpha particle has twice the charge of a proton, it has approximately four times the mass, resulting in a lower overall charge-to-mass ratio.

9. What is the ionizing power of alpha particles?

Alpha particles have very high ionizing power, meaning they can create many ion pairs per unit length of their path. This is due to their large mass and charge, which allows them to interact strongly with electrons in atoms.

10. What is the significance of the alpha particle's binding energy?

The alpha particle has a high binding energy per nucleon, making it a very stable configuration. This stability explains why it's a common product in radioactive decay and plays a role in nuclear fusion processes.

11. How do alpha particles contribute to stellar nucleosynthesis?

Alpha particles play a crucial role in stellar nucleosynthesis, particularly in the triple-alpha process. This process, which occurs in stars, involves the fusion of three helium-4 nuclei (alpha particles) to form carbon-12, a key step in the production of heavier elements.

12. Why do alpha particles have a positive charge?

Alpha particles have a positive charge because they consist of two protons, each with a +1 charge, and two neutrons, which have no charge. The total charge is therefore +2.

13. Can alpha particles penetrate human skin?

No, alpha particles cannot penetrate human skin. They are easily stopped by a few centimeters of air or a sheet of paper due to their relatively large size and charge, which causes them to interact strongly with matter.

14. What is the typical energy range of alpha particles emitted in radioactive decay?

The typical energy range of alpha particles emitted in radioactive decay is between 3 and 7 MeV (million electron volts), though some can have energies up to 10 MeV.

15. How does the velocity of an alpha particle compare to that of other types of radiation?

Alpha particles typically have lower velocities compared to beta particles or gamma rays due to their larger mass. Their speed is usually around 5-7% of the speed of light, while beta particles can reach up to 99% of the speed of light.

16. How do alpha particles interact with matter?

Alpha particles interact strongly with matter due to their positive charge and relatively large mass. They quickly lose energy through ionization and excitation of atoms in the material they pass through, resulting in a short range.

17. How do alpha particles contribute to the understanding of atomic structure?

Alpha particles played a crucial role in the development of our understanding of atomic structure. Rutherford's famous gold foil experiment, which used alpha particles, led to the discovery of the atomic nucleus and the nuclear model of the atom.

18. How are alpha particles used in smoke detectors?

In ionization smoke detectors, a small amount of americium-241 emits alpha particles that ionize air molecules. This creates a small electric current. When smoke enters the chamber, it disrupts this current, triggering the alarm.

19. What is the difference between alpha particles and alpha radiation?

Alpha particles are the physical particles (two protons and two neutrons) emitted during radioactive decay, while alpha radiation refers to the stream or emission of these particles. Alpha radiation is a type of ionizing radiation caused by alpha particles.

20. Can alpha particles be accelerated in particle accelerators?

Yes, alpha particles can be accelerated in particle accelerators. In fact, some of the earliest particle accelerators, like cyclotrons, were designed to accelerate alpha particles for nuclear physics experiments.

21. How do alpha particles affect DNA?

Alpha particles can cause significant damage to DNA if they come into direct contact with living cells. Their high ionizing power can break chemical bonds in DNA molecules, potentially leading to mutations or cell death. However, their short range means they are generally only harmful if ingested or inhaled.

22. What is alpha decay, and how does it relate to alpha particles?

Alpha decay is a type of radioactive decay where an atomic nucleus emits an alpha particle (two protons and two neutrons). This process reduces the atom's mass number by four and its atomic number by two, transforming it into a different element.

23. What is the significance of the helium nucleus in understanding alpha particles?

The helium nucleus is identical to an alpha particle. This connection helps in understanding the structure and properties of alpha particles, as well as their behavior in nuclear reactions and decay processes.

24. How do alpha particles compare to helium ions?

Alpha particles and helium ions (He2+) are essentially the same thing - both are helium nuclei with two protons and two neutrons. The main difference is context: "alpha particle" is typically used in the context of radioactive decay, while "helium ion" is more general and can refer to ionized helium in various settings.

25. How do alpha particles contribute to the formation of radon gas?

Radon gas is produced by the alpha decay of radium in the ground. As radium decays, it emits alpha particles, transforming into radon. The emission of alpha particles is thus directly responsible for the formation of this radioactive gas.

26. How does the range of alpha particles in air compare to that of beta particles?

Alpha particles have a much shorter range in air compared to beta particles. Typically, alpha particles can travel only a few centimeters in air, while beta particles can travel up to several meters.

27. What is the relationship between alpha particles and cosmic rays?

While cosmic rays consist of various types of particles, a small fraction of them are alpha particles. These high-energy alpha particles originate from sources outside the Earth's atmosphere and can provide information about astrophysical processes.

28. How do alpha particles interact with magnetic fields?

Alpha particles, being positively charged, are deflected by magnetic fields according to the Lorentz force. The direction of deflection is perpendicular to both the magnetic field and the particle's velocity, following the right-hand rule.

29. What is meant by the "stopping power" of a material for alpha particles?

Stopping power refers to the ability of a material to slow down or stop alpha particles. It's typically measured as the energy loss per unit path length and depends on the material's density and atomic composition. Materials with high stopping power can effectively shield against alpha radiation.

30. How does temperature affect the behavior of alpha particles?

Temperature generally doesn't significantly affect the behavior of alpha particles themselves, as their energies are much higher than thermal energies. However, in extremely hot environments like stellar interiors, temperature can affect the likelihood of alpha particle interactions and fusion processes.

31. What is the role of alpha particles in radiotherapy?

Alpha particles are sometimes used in targeted alpha therapy, a form of radiotherapy for certain cancers. Due to their short range and high ionizing power, they can deliver localized damage to cancer cells while minimizing harm to surrounding healthy tissue.

32. What is the significance of the alpha particle's de Broglie wavelength?

The de Broglie wavelength of an alpha particle is typically very small due to its relatively large mass. This wavelength is important in quantum mechanics and helps explain why alpha particles generally behave classically rather than exhibiting significant wave-like properties.

33. How do alpha particles contribute to the study of nuclear structure?

Alpha particles are used as probes in nuclear physics experiments. By observing how alpha particles scatter off nuclei, scientists can gain information about nuclear structure, sizes, and forces, similar to Rutherford's original experiments.

34. What is the relationship between alpha particles and the strong nuclear force?

The strong nuclear force is responsible for holding the protons and neutrons together within an alpha particle. The stability of alpha particles is a testament to the strength of this force at short distances, overcoming the electrostatic repulsion between the protons.

35. How do alpha particles contribute to the formation of atmospheric helium?

Some of the helium in Earth's atmosphere is produced by the decay of radioactive elements in the Earth's crust that emit alpha particles. These alpha particles, being helium nuclei, can capture electrons to form helium atoms, contributing to atmospheric helium content.

36. What is the significance of alpha particles in dating geological samples?

Alpha particles play a role in radiometric dating techniques, particularly in uranium-lead dating. The emission of alpha particles during the decay chain of uranium to lead allows geologists to determine the age of rocks and minerals.

37. How do alpha particles interact with semiconductors?

When alpha particles interact with semiconductors, they create electron-hole pairs along their path. This property is used in some radiation detectors. However, in electronic devices, alpha particles can cause soft errors or damage, which is a concern in space-based electronics.

38. What is the tunneling effect in relation to alpha decay?

The tunneling effect explains how alpha particles can escape from the nucleus despite the strong nuclear force. Quantum tunneling allows the alpha particle to penetrate the potential barrier that classical physics would forbid, enabling alpha decay to occur.

39. How do alpha particles contribute to the study of fusion reactions?

Alpha particles are both reactants and products in many fusion reactions. For example, in deuterium-tritium fusion, an alpha particle is produced. Studying the behavior and energy of these alpha particles provides crucial information about fusion processes and plasma conditions.

40. What is the significance of the alpha particle's gyroradius in plasma physics?

The gyroradius (or Larmor radius) of an alpha particle in a magnetic field is important in plasma physics, particularly in fusion research. It affects how alpha particles behave in magnetic confinement devices and how they transfer energy to the plasma.

41. How do alpha particles interact with neutrons?

Alpha particles do not interact strongly with neutrons due to the lack of charge on neutrons. However, in certain high-energy collisions, alpha particles can break apart upon collision with neutrons, leading to various nuclear reactions.

42. What is the role of alpha particles in the proton-proton chain reaction in stars?

In the proton-proton chain, which is the primary energy source for stars like our Sun, alpha particles are produced as end products. The formation of these stable helium nuclei releases energy, driving stellar processes.

43. How do alpha particles contribute to the study of cosmic ray air showers?

While primary cosmic rays are often protons or heavier nuclei, alpha particles can be produced in secondary cosmic ray air showers. Studying these alpha particles helps scientists understand the composition and energy of primary cosmic rays.

44. What is the significance of alpha particles in understanding nuclear shell structure?

The stability of alpha particles relates to the nuclear shell model. The fact that nuclei with "magic numbers" of protons or neutrons (which complete shells) are often more stable and more likely to emit or absorb alpha particles has helped refine our understanding of nuclear structure.

45. How do alpha particles interact with superconductors?

Alpha particles can break Cooper pairs in superconductors, temporarily disrupting superconductivity in small regions. This interaction is studied both for its fundamental physics interest and for practical concerns in superconducting devices used in high-radiation environments.

46. What is the role of alpha particles in the CNO cycle in stars?

In the CNO (Carbon-Nitrogen-Oxygen) cycle, which is the dominant energy production mechanism in stars more massive than the Sun, alpha particles are produced as part of the reaction chain. The emission of these alpha particles contributes to the energy output of the star.

47. How do alpha particles contribute to the formation of cosmic dust?

Alpha particles, as products of radioactive decay, can play a role in the alteration of cosmic dust grains. Over long periods, alpha decay of radioactive elements within dust grains can cause structural changes and contribute to the evolution of interstellar and interplanetary dust.

48. What is the significance of alpha particles in understanding nuclear fission?

While alpha particles are not directly involved in fission, the stability of alpha particles (helium nuclei) influences nuclear stability and fission processes. The tendency of heavy nuclei to form clusters, including alpha-particle-like structures, affects their likelihood to undergo fission.

49. How do alpha particles contribute to the study of solar wind?

Alpha particles are a significant component of the solar wind, making up about 4% of its composition. Studying these solar wind alpha particles provides information about solar processes and the Sun's outer layers.

50. What is the role of alpha particles in neutron activation analysis?

While neutrons are the primary particles used in neutron activation analysis, alpha particles can sometimes be used in a similar technique called charged particle activation analysis. This can be useful for analyzing the composition of materials, particularly for light elements.

51. How do alpha particles interact with liquid crystals?

Alpha particles can cause ionization and excitation in liquid crystals, potentially altering their optical and electrical properties. This interaction is studied both for fundamental understanding and for potential applications in radiation detection.

52. What is the significance of alpha particles in understanding nuclear magic numbers?

The stability of nuclei with certain "magic numbers" of protons or neutrons is partly explained by the tendency to form alpha-particle-like substructures. This connection between alpha particles and nuclear shell structure has been crucial in developing models of the atomic nucleus.

53. How do alpha particles contribute to the production of medical isotopes?

Alpha particles, when used as projectiles in particle accelerators, can induce nuclear reactions that produce certain medical isotopes. For example, the production of astatine-211, used in some cancer treatments, involves alpha particle bombardment of bismuth.

54. What is the role of alpha particles in the study of nuclear astrophysics?

In nuclear astrophysics, understanding alpha-particle interactions is crucial for modeling stellar evolution and nucleosynthesis. Alpha-capture reactions, where nuclei absorb alpha particles to form heavier elements, are key processes in stellar environments.

55. How do alpha particles contribute to our understanding of fundamental forces?

The study of alpha particles and their interactions has contributed to our understanding of both the strong nuclear force (which binds the particles together) and the electromagnetic force (which governs their interactions with matter and fields). These studies have been crucial in the development and testing of theories in particle physics and quantum mechanics.