The key difference between radioactivity and radiation is that radioactivity is the process by which certain elements release radiation whereas radiation is the energy or energetic particles that are released by radioactive elements.
Radioactivity was a natural process, existing in the universe since time immemorial. Thus, it was a chance discovery by Henry Becquerel in 1896 that the world came to know about it. Furthermore, the scientist Marie Curie explained this concept in 1898 and earned a Nobel Prize for her work. We refer the type of radioactivity taking place in the world (read stars) on its own as natural radioactivity while that which man induces as artificial radioactivity.
CONTENTS
1. Overview and Key Difference
2. What is Radioactivity
3. What is Radiation
4. Side by Side Comparison – Radioactivity vs Radiation in Tabular Form
5. Summary
What is Radioactivity?
Radioactivity is the spontaneous nuclear transformation that results in the formation of new elements. In other words, radioactivity is the capability to release radiation. There are a large number of radioactive elements. In a normal atom, the nucleus is stable. However, in the nuclei of radioactive elements, there is an imbalance of neutrons to protons ratio; thus, they are not stable. Thus, in order to become stable, these nuclei will emit particles, and this process is the radioactive decay.
Figure 01: Collisions and Radioactive Decay in a Diagram
Each radioactive element has a rate of decaying, which we name as its half-life. Half-life tells the time that a radioactive element requires to decrease to one half of its original quantity. The resulting transformations include Alpha particle emission, Beta particle emission and orbital electron capture. Alpha particles emitted from a nucleus of an atom when the neutron to proton ratio is too low. For example, Th-228 is a radioactive element which can emit alpha particles with different energies. When a beta particle emits, a neutron inside a nucleus converts into a proton by emitting a beta particle. P-32, H-3, C-14 are pure beta emitters. Radioactivity is measured by the units, Becquerel or Curie.
What is Radiation?
Radiation is the process where waves or energy particles (e.g., Gamma rays, x-rays, photons) travel through a medium or space. The unstable nuclei of radioactive elements are trying to become stable by emitting radiation. Radiation is in two types as ionizing or non-ionizing radiation.
Ionizing radiation has high energy, and when it collides with an atom, that atom gets ionized, emitting a particle (e.g. an electron) or photons. The emitted photon or particle is radiation. The initial radiation will continue to ionize other materials until all its energy is used up.
Figure 02: Alpha, Beta and Gamma Radiation
Non-ionizing radiations do not emit particles from other materials, because their energy is lower. However, they carry enough energy to excite electrons from ground level to higher levels. They are electromagnetic radiation; thus, have electric and magnetic field components parallel to each other and to the wave propagation direction.
Alpha emission, beta emission, X-rays, gamma rays are ionizing radiations. Alpha particles have a positive charge, and they are similar to the nucleus of a He atom. They can travel across a very short distance (i.e. a few centimetres). Beta particles are similar to electrons in size and charge. They can travel a longer distance than alpha particles. Gamma and x-rays are photons, not particles. Gamma rays from inside a nucleus and x-rays form in an electron shell of an atom. Ultraviolet, infrared, visible light, microwave are some of the examples to non-ionizing radiation.
What is the Difference Between Radioactivity and Radiation?
Radioactivity is the spontaneous nuclear transformation that results in the formation of new elements whereas radiation is the process where waves or energy particles (e.g., Gamma rays, x-rays, photons) travel through a medium or space. Hence, we can say that the key difference between radioactivity and radiation is that radioactivity is the process by which certain elements release radiation whereas radiation is energy or energetic particles that are released by radioactive elements. In brief, radioactivity is a process while radiation is a form of energy.
As another important difference between radioactivity and radiation we can say the unit of measurement. That is; the unit of measurement for radioactivity is either Becquerel or Curie whereas, for radiation, we use units of measurement of energy such as electron volts (eV).
Summary – Radioactivity vs Radiation
Radioactivity and radiation are very important terms regarding radioactive materials. The key difference between radioactivity and radiation is that radioactivity is the process by which certain elements release radiation whereas radiation is energy or energetic particles that are released by radioactive elements.
Reference:
1. “Radioactive Decay.” Wikipedia, Wikimedia Foundation, 18 Oct. 2018. Available here
2. “Radiation.” Wikipedia, Wikimedia Foundation, 29 Aug. 2018. Available here
Image Courtesy:
1.”NuclearReaction”By Kjerish – Own work, (CC BY-SA 4.0) via Commons Wikimedia
2.”Alfa beta gamma radiation penetration”By Stanneredderivative work (CC BY 2.5) via Commons Wikimedia