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. Alpha particles can easily be shielded by a single sheet of paper and cannot penetrate the outer dead layer of skin, so they pose no danger when their source is outside the human body.
Beta particles are essentially electrons emitted from the nucleus of a radioactive atom. They are lighter than alpha particles, and can travel farther in air, up to several yards. Very energetic beta particles can penetrate up to one-half an inch through skin and into the body. Effects from exposure to radiation include leukemia, birth defects, and many forms of cancer.
Most external radiation is absorbed by the environment; for example, most ultraviolet radiation is absorbed by the ozone layer, preventing deadly levels of ultraviolet radiation to come in contact with the surface of the earth.
Sunburn is an effect of UV radiation damaging skin cells, and prolonged exposure to UV radiation can cause genetic information in skin cells to mutate, leading to skin cancer. Alpha, beta, and gamma rays also cause damage to living matter, in varying degrees. Alpha particles have a very small absorption range, and thus are usually not harmful to life, unless ingested, due to its high ionizing power. Beta particles are also damaging to DNA, and therefore are often used in radiation therapy to mutate and kill cancer cells.
Gamma rays are often considered the most dangerous type of radiation to living matter. Unlike alpha and beta particles, which are charged particles, gamma rays are instead forms of energy. They have large penetrating range and can diffuse through many cells before dissipating, causing widespread damage such as radiation sickness. Because gamma rays have such high penetrating power and can damage living cells to a great extent, they are often used in irradiation, a process used to kill living organisms.
There are several methods to measure radiation; hence, there are several radiation units based on different radiation factors. Radiation units can measure radioactive decay, absorbed dosage, and human absorbed doses. Bq and Ci measure radioactive decay, while Gy and Rad measures absorbed doses. Sv and Rem measure absorbed doses in Gy and Rad equivalents. Rem takes into account different radiation types and the speed of particles.
Below is a chart to help organize the different units:. The most commonly used unit is the "rad," which stands for "radiation absorbed dose," and the "rem," which stands for "radiation equivalent for man. Rem is the rad multiplied by the relative biological effectiveness, which is most often expressed as the variable "Q. Introduction There are many types of radiation , but the two most common are electromagnetic radiation and ionizing radiation.
Primary Electrons and Secondary Ionization The main effect radiation has on matter is its ability to ionize atoms to become ions, a phenomenon known as ionization , which is very similar to the photoelectric effect. Effects of Radiation on Living Matter Prolonged exposure to radiation often has detrimental effects on living matter. Radiation Dosage and Decay There are several methods to measure radiation; hence, there are several radiation units based on different radiation factors.
Concept Review Questions Classify the following interactions that occur as either primary ionization, secondary ionization, or electron excitement. Photons are ejected from the atom.
An electron from a nearby atom is ejected, knocking out an electron from a neighboring atom. Electrons are ejected from the atom. Describe the difference between ionizing and non-ionizing radiation. Explain why radiation has such a harmful effect on living matter. Consider modern microwave oven used in kitchens. Are the microwaves ejected to heat water and food harmful to the human body? The ionizing radiation that is emitted can include alpha particles alpha particles A form of particulate ionizing radiation made up of two neutrons and two protons.
Alpha particles pose no direct or external radiation threat; however, they can pose a serious health threat if ingested or inhaled. Some beta particles are capable of penetrating the skin and causing damage such as skin burns. Beta-emitters are most hazardous when they are inhaled or swallowed. Gamma rays can pass completely through the human body; as they pass through, they can cause damage to tissue and DNA. Radioactive decay occurs in unstable atoms called radionuclides.
The energy of the radiation shown on the spectrum below increases from left to right as the frequency rises. Other agencies regulate the non-ionizing radiation that is emitted by electrical devices such as radio transmitters or cell phones See: Radiation Resources Outside of EPA.
Alpha particles come from the decay of the heaviest radioactive elements, such as uranium , radium and polonium. Even though alpha particles are very energetic, they are so heavy that they use up their energy over short distances and are unable to travel very far from the atom.
The health effect from exposure to alpha particles depends greatly on how a person is exposed. Alpha particles lack the energy to penetrate even the outer layer of skin, so exposure to the outside of the body is not a major concern. Inside the body, however, they can be very harmful. If alpha-emitters are inhaled, swallowed, or get into the body through a cut, the alpha particles can damage sensitive living tissue. The way these large, heavy particles cause damage makes them more dangerous than other types of radiation.
The ionizations they cause are very close together - they can release all their energy in a few cells. This results in more severe damage to cells and DNA. These particles are emitted by certain unstable atoms such as hydrogen-3 tritium , carbon and strontium Beta particles are more penetrating than alpha particles, but are less damaging to living tissue and DNA because the ionizations they produce are more widely spaced. They travel farther in air than alpha particles, but can be stopped by a layer of clothing or by a thin layer of a substance such as aluminum.
However, as with alpha-emitters, beta-emitters are most hazardous when they are inhaled or swallowed. Unlike alpha and beta particles, which have both energy and mass, gamma rays are pure energy.
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