Alpha Beta Gamma Rays Properties
Alpha, beta, and gamma rays radiation spontaneously radioactive decay to change the atomic nucleus by the irradiation of charged particles which are accompanied by the emission of energy in the form of the electromagnetic spectrum radiation. Among these three particles, alpha and beta particles are deflected in the magnetic and electric field but gamma rays made of electromagnetic waves with very small wavelengths. The charge, mass, velocity, and penetrating properties of alpha-beta particles, and gamma rays are different. The emission of alpha-beta and gamma rays from different radiation sources independent of pressure, temperature, pH scale, etc of surroundings. This is due to the activation energy for radioactive alpha beta and gamma rays radiation is zero and uses first-order chemical kinetics to derive rate laws in nuclear reaction in learning chemistry or physics.
Other particles rather then alpha, beta or gamma rays, like positron decay from the radioactive nucleus has similar properties of beta rays radiation but the relative charge carries the positive signs. Therefore, nuclear equilibrium involves the emission of alpha, beta, gamma, and positrons rays from inside the nucleus. But in chemical equilibrium reactions involve some loss, gain, or sharing of outer electrons orbital by breaking and forming new chemical bonds within the reactant and product atoms.
Discovery of Alpha Beta and Gamma Rays
- In 1896 the French scientist Henrey Becquerel discovered alpha, beta, or gamma rays radiation. While investigating the nature of electromagnetic spectrum radiation (x -rays) discovered by Rontgen a few months earlier. He found that a photographic plate was shielding by a sample of potassium – uranyl – sulfate placed. Therefore, he obtains the conclusion that some radiation particles emitting from the uranium compound could shield the cover of the photographic plate. But the properties of alpha, beta, or gamma rays radiations were very similar to those of x -rays.
- Marie Curie found the activity of mineral pitchblende present in our environment. He shows that the activity of this compound greater than the uranium content. Therefore, in 1898 Pierre and Marie Curie isolated two new chemical elements like Polonium and Radium by the emission of alpha, beta, and gamma rays.
- In 1900, Debierne and Giesel discovered actinium which emitted alpha, beta, or gamma rays.
Properties of Alpha Particles
Alpha particle consists of a stream of positively charged particle which carries +2 charge and mass number 4. Rutherford showed that the alpha particle is identical to the nuclei of the helium atom. Therefore, the alpha particle is doubly charged helium ion (He+2) with atomic number 2 and mass number 4.
But when an alpha particle ejected from within the nucleus of an atom, the mother element loses two units of atomic number and four units of mass number. Checking from the periodic table elements we concluded that the daughter element is an isotope of mother elements. 92U238 ⇒ 90Th234 + 2He4 (alpha-ray).
Properties of Beta Particles
The easy deflection of the beta particle in a magnetic or electric field proves that this ray made up of a stream of negatively charged particles. Hence the e/m values of beta ray identical to that of an electron, e/m = 1.77 × 108 coulombs/gm. Therefore the ejection of a beta particle (mass number 0 and charge 1) results in the transformation of a neutron into a proton. When a beta particle emitted from the nucleus, the daughter nucleus has an atomic number one unit greater than that of the mother nucleus. Therefore, 90Th234 ⇒ 91Pa234 + -1e0 (beta).
Beta Radiation and Electron Emission
Although beta particles and electrons are identical in their electrical nature and charge/mass ratio. But the fundamental difference between them,
- The ejection of an electron converts a neutral atom into a positively charged ion but leaves the nucleus undisturbed.
- But the ejection of a beta particle changes the very composition of the nucleus and produces an atom of the next higher atomic number.
Properties of Gamma Rays
Properties of gamma rays emission consist of electromagnetic spectrum radiation of very short wavelength (λ ∼ 0.005 – 1 Å). These are high energy photons. During all nuclear reactions there occurs a change in the nuclear power of the nucleus due to the emission of alpha or beta particles.
The unstable, excited nucleus resulting in the emission of photons or gamma rays irradiation. After the emission of gamma rays, the nucleus drops a more stable energy state. Therefore, gamma rays do not carry charge or mass. Hence the irradiation of gamma rays cannot change the mass number or atomic nucleus properties.
Properties of Positron Emission
Curies and Rutherford discover another mode of nuclear transformation rather than alpha, beta or gamma rays. This involves the ejection of a positron from within the nucleus. Therefore, this ejection made by the conversion of a proton into a neutron. The ejection of positron lowers the atomic number one unit but leaves the mass number unchanged.
1H1 ⇒ 0n1 + +1e0
51Sb120 ⇒ 50Sn120 + +1e0
Neutrino radiation in Beta Decay
According to the principle of conservation of energy or angular momentum, breaking down of a neutron into a proton, the beta particle creates a problem. Particles like neutron, proton, and electron have the spin angular momentum ± ½ (h/2π) each.
0n1 ⇒ 1H1 + -1e0
The above equation balance with respect to change but not balance with respect to angular momentum. Because of the angular momentum of proton and electron = +½ (h/2π) each. Therefore, Pauli postulated that when a beta particle ejected another tiny neutral particle namely neutrino. The mass of the neutrino = 0.00002 with respect to the oxygen scale. The ejection of an electron from within the nucleus should be represented as Neutron → proton + electron + neutrino.
Alpha Beta Gamma Rays and Chemical Reactions
Nuclear particles reactions are different from chemical reactions with the following respects
- Chemical reactions involve some loss, gain, or forming a chemical bond or changing oxidation number in the reactant and product atoms. Such reactions cannot alter the composition of the nuclei so that the atomic number of the chemical reactions unchanged. On the other hand, the radioactivity cause of nuclear irradiation involves the radiation of alpha, beta particles, or gamma rays. Thus these reactions lead to a change in the atomic number of the nucleus.
- The nuclear reactions are accompanied by nuclear energy changes which far exceed the chemical energy changes in redox reactions. The energy evolved in the radioactive radiation decay of 1-gm radium 5000 times larger than the specific heat released when 1-gm radium combine with chlorine.
- Different isotopes of the same element show identical chemical properties since they possess the same electronic configuration. But these isotopes after emission of alpha, beta, and gamma rays possess different nuclear properties.
- The chemical reactions are dependent on external conditions such as temp, pressure, pH scale, etc. but nuclear reactions are not.
In learning chemistry or physics, the radiation emitting from radioactive substance or molecule consists of three different kinds of rays like alpha, beta, and gamma rays. Among alpha or gamma rays, beta rays use to discover free electrons in chemical elements during the ionization of gases in the gas discharge tubes.