The radioactive decay law states that “The probability per unit time that a nucleus will decay is a constant, independent of time”.

Terms in this set (4)

• Alpha Decay. 2 protons and 2 neutrons lost. Atomic number down by 2, atomic mass down by 4.
• Beta Decay. 1 neutron turns into a proton. Atomic number up by 1.
• Positron Emission. 1 proton turns into a neutron.
• Gamma Decay. Due to a high energy nucleus, energy is given off and nucleus becomes stable.

Alpha Decay Equation In nuclear physics, Alpha decay Equation for thorium-232 can be written as – _{90}^{232}/textrm{Th}/rightarrow _{88}^{228}/textrm{Ra}+_{2}^{4}/textrm{He} Where, _{90}^{232}/textrm{Th} is the unstable Thorium-232 parent nucleus. _{88}^{228}/textrm{Ra} is the stable Radium-228 daughter nucleus.

The law of radioactive decay is probably the most important law of radioactivity. When a nucleus undergoes decay through the emission of an alpha particle or a beta electron, it transforms: this allows for the conversion of radium into radon, for instance, or of tritium into helium.

Suppose N is the size of a population of radioactive atoms at a given time t, and dN is the amount by which the population decreases in time dt; then the rate of change is given by the equation dN/dt = −λN, where λ is the decay constant.

Beta decay occurs when, in a nucleus with too many protons or too many neutrons, one of the protons or neutrons is transformed into the other. In beta minus decay, a neutron decays into a proton, an electron, and an antineutrino: n Æ p + e – +.

Some beta particles are capable of penetrating the skin and causing damage such as skin burns. However, as with alpha-emitters, beta-emitters are most hazardous when they are inhaled or swallowed.

Beta plus decay happens when a proton changes into a neutron, giving out a positron. An example of beta plus decay is the isotope nitrogen-12, which has too few neutrons. If a proton changes into a neutron, giving out a beta plus particle, the nucleus becomes one of carbon-12, which is extremely stable.

If the radioactive source is inside the body, perhaps after being swallowed or breathed in: alpha radiation is the most dangerous because it is easily absorbed by cells. beta and gamma radiation are not as dangerous because they are less likely to be absorbed by a cell and will usually just pass right through it.

Exposure to high doses of radiation over a short period of time can cause radiation sickness (sometimes called radiation poisoning or acute radiation syndrome) and even death.

α ALPHA – can be stopped after traveling through about 1.2 inches of air, about 0.008 inches of water, or a piece of paper or skin. A thin piece of paper, or even the dead cells in the outer layer of human skin, provides adequate shielding because alpha particles can’t penetrate it.

Alpha particles may be ejected from the nucleus of an atom during radioactive decay. They are relatively heavy, and only travel about an inch in air. Shielding this very penetrating type of ionizing radiation requires thick, dense material such as several inches of lead or concrete.

An alpha particle is identical to the nucleus of a helium-4 atom, which consists of two protons and two neutrons. It has a charge of +2 e and a mass of 4 u. For example, uranium-238 decays to form thorium-234.

Alpha decay occurs when a nucleus is unstable because it has too many protons. The nucleus emits an alpha particle and energy. An alpha particle consists of two protons and two neutrons, which is actually a helium nucleus. Losing the protons and neutrons makes the nucleus more stable.

If you’re exposed to significant radiation, your thyroid will absorb radioactive iodine (radioiodine) just as it would other forms of iodine. The radioiodine is eventually cleared from the body in urine. If you take potassium iodide, it may fill “vacancies” in the thyroid and prevent the absorption of radioiodine.