Radioactive Emissions

Written by J.A Dobado | Last Updated on April 22, 2024

Between 1896 and 1903, scientists discovered that not all radioactive elements emit the same radiation. Some emit more powerful radiation than others, each of which transforms the nucleus in a different way.

When radiation from a sample of a radioactive element, such as radium (Ra), is subjected to the action of a magnetic field, three types of radioactive emissions are determined: alpha particles, beta particles and gamma rays.

Alpha particles

They are a stream of positively charged (+) particles. They are formed by two protons and two neutrons, which is equivalent to helium atoms (He). Because the mass and volume of a-particles are relatively high, these radiations travel at a lower speed than Beta or Gamma radiations, therefore, they have a low penetrating power. In addition, these particles easily collide with air molecules and in each collision they lose part of their energy, until they are stopped or absorbed by some other nucleus in their path. At the same time, if the particles collide with the peripheral electrons of an atom, these can be torn away by them, causing the atom to ionize. Consequently, alpha particles have great ionizing power.

Beta particles

They are electrons (negative charge) launched, at high velocities, from an unstable nucleus. Beta particles are 7,000 times smaller than alpha particles and travel at a speed close to the speed of light, a condition that allows them to pass through the lattice of nuclei and electrons of some kinds of matter. In short, they have a medium penetration power, but greater than that of alpha particles. Electrons do not exist in the nucleus, they are formed from a neutron (in unstable nuclei) according to the reaction:

When a nucleus emits a beta particle, its atomic number increases by one unit and its mass number is unaffected.

Gamma rays

These are light waves, i.e. electromagnetic radiation identical to that of light, but with a much higher energy content, they have no electric charge and therefore do not suffer deviation in the presence of an electric field. Their danger lies in the fact that they are highly mutagenic for living cells.

The ionizing power of radioactive emissions varies inversely to their penetrating power. Thus, radiation that has a very low capacity to penetrate matter has a very high ionizing power. It has been calculated that their ionizing power is 100 times higher than that of beta radiation and these, 100 times higher than that of gamma radiation.

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