Difference Between Proton and Positron

Main Difference – Proton vs Positron

Atoms are the building blocks of all matter. An atom is composed of a nucleus and an electron cloud. The nucleus contains protons and neutrons along with some other particles such as alpha particles and beta particles. A proton is a subatomic particle having a positive electrical charge (+1). A positron is also a positively charged subatomic particle. The main difference between proton and positron is that the mass of a proton is considerably higher than that of a positron.

Key Areas Covered

1. What is a Proton
– Definition, Properties
2. What is a Positron
– Definition, Annihilation
3. What are the Similarities Between Proton and Positron
– Outline of Common Features
4. What is the Difference Between Proton and Positron
– Comparison of Key Differences

Key Terms: Annihilation, Antielectron, Atomic Mass, Atomic Number, Atoms, Beta Decay, Electron, Positrons, Protons

What is a Proton

A proton is a subatomic particle with a positive electrical charge of +1. A proton is symbolized by “p” or “p⁺”. Protons, together with neutrons, form the atomic nucleus, which is the core of an atom. The electrical charge of a proton is +1.6022 x 10^-19 C (Coulomb). The atomic charge of a proton is given as +1. The mass of a proton is 1.6726 x 10^-24 g. But the atomic mass of a proton is given as 1.0073 amu (atomic mass units). This is generally used as 1 amu. But the mass of a proton is slightly less than that of a neutron.

The atomic number, i.e., the number of protons in the nucleus of an atom, of a chemical element is a unique property for each and every element. This is because a chemical element is recognized according to its atomic number. The atomic number is the total number of protons present in an atom. The periodic table of elements is built based on the atomic numbers of chemical elements. Therefore, the periodic table consists of chemical elements arranged in the ascending order of the protons present in their atoms.

Each and every atom is composed of at least one proton. The smallest neutral atom is a hydrogen atom. It has one proton. Isotopes of a chemical element are the atoms having the same atomic number (number of protons) and different numbers of neutrons.

Figure 1: Protium is an isotope of hydrogen which has one proton and one electron

A free proton is found to be stable. A free proton is a proton that is not attached to neutrons or electrons. The free proton does not break or convert into other particles spontaneously. However, protons are known to be converted into neutrons via a process called electron capture. But this conversion is reversible. Free protons undergo this conversion when required energy is provided.

p⁺ + e^– ↔ n + Ve

What is a Positron

Positron is a subatomic particle that is considered as an antielectron. It is the antiparticle of the electron. Therefore, the positron has a +1 electrical charge. The mass of positron is exactly equivalent to the mass of an electron; 9.1094 x 10^-28 g. The atomic mass of positron is 0.00054858 amu. The electrical charge is opposite to that of the electron: +1.6022 x 10^-19 C.

Positrons are naturally produced via beta (β⁺) decay. This form of decay occurs in radioactive isotopes. This positron formation can be either natural or artificial based on the nature of radioisotope (radioisotope can be either natural or artificial).

Positron Annihilation

Figure 2: Annihilation Produces Two or More Gamma Ray Photons

Annihilation is a process in which a positron collides with an electron which causes the production of two or more gamma ray photons, if the collision occurs at a low energy.

Similarities Between Proton and Positron

Both are subatomic particles.
Both have +1 atomic charge.
Both have an electrical charge of +1.6022 x 10^-19

Definition

Proton: A proton is a subatomic particle with a positive electrical charge of +1.

Positron: Positron is the antiparticle or the antimatter counterpart of the electron.

Mass

Proton: The mass of a proton is 1.6726 x 10^-24 g.

Positron: The mass of a positron is 9.1094 x 10^-28 g.

Atomic Mass

Proton: The atomic mass of a proton is given as 1.0073 amu

Positron: The atomic mass of positron is 0.00054858 amu.

Nature

Proton: Protons are the major subatomic particles that are responsible for the atomic number of a chemical element.

Positron: Positrons are the antiparticles of electrons.

Annihilation

Proton: Protons do not undergo annihilation.

Positron: Positrons undergo annihilation.

Conclusion

Although both protons and positrons are positively charged subatomic particles, there are differences between them. The main difference between proton and positron is that the mass of a proton (1.6726 x 10^-24 g) is considerably higher than that of a positron (9.1094 x 10^-28 g).

Reference:

1. “Sub-Atomic Particles.” Chemistry LibreTexts, Libretexts, 21 July 2016, Available here.
2. “Positron.” Wikipedia, Wikimedia Foundation, 24 Jan. 2018, Available here.
3. “Positron.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 3 June 2013, Available here.

Image Courtesy:

1. “Protium” By Blacklemon67 at English Wikipedia – Own work (Original text: I (Blacklemon67 (talk)) (Public Domain) via Commons Wikimedia
2. “Mutual Annihilation of a Positron Electron pair” By Manticorp – Own work (CC BY-SA 3.0) via Commons Wikimedia