displacement law In , Soddy and Fajan framed the displacement laws governing the daughter nucleus produced during an alpha and beta decay. They are stated below: (i) When a radioactive element emits an alpha particle, a daughter nucleus is formed whose mass number is less by units and the atomic number is less by units, than the mass number and atomic number of the parent nucleus. (ii) When a radioactive element emits a beta particle, a daughter nucleus is formed whose mass number is the same and the atomic number is more by unit, than the atomic number of the parent nucleus. .
ALPHA, BETA AND GAMMA RAYS When a radioactive nucleus undergoes radioactivity, it emits harmful radiations. These radiations are usually comprised of any of the three types of particles. They are alpha(α), beta (β) and gamma(γ) rays. Uranium, named after the planet Uranus, was discovered by Martin Klaproth, a German chemist in a mineral called pitchblende.
. . Properties of Alpha, Beta and Gamma rays These three particles possess certain similarities and dissimilarities in their properties as listed below in Table . .
Table . Properties of alpha, beta and gamma rays Properties α rays β rays γ rays What are they? Helium nucleus ( He ) consisting of two protons and two neutrons. They are electrons ( – e ), basic elementary particle in all atoms.
They are electromagnetic waves consisting of photons. Charge Positively charged particles. Charge of each alpha particle = +2e Negatively charged particles. Charge of each beta particle = –e Neutral particles.
Charge of each gamma particle = zero Ionising power time greater than β rays and , times greater than γ rays Comparatively low Very less ionization power Penetrating power Low penetrating power (even stopped by a thick paper) Penetrating power is greater than that of α rays. They can penetrate through a thin metal foil. They have a very high penetrating power greater than that of β rays. They can penetrate through thick metal blocks.
Effect of electric and magnetic field Deflected by both the fields.