5.1 Natural Radioactivity

5.1 Natural Radioactivity

• Stable nuclei are found in most naturally occurring isotopes of elements.

• An atom is converted into an atom of a different element when there is a change in the number of protons in the nucleus.

• The elements with atomic numbers of 93 and higher are produced in nuclear laboratories.

• The mass number in the upper left corner and the atomic number in the lower left corner are the atomic symbols.
• The atomic number is equal to the number of protons in the nucleus.
• A radioactive isotope of carbon used for archaeological dating has a mass number of 14 and an atomic number of 6.

• The mass number is written after the element's 6 protons name or symbol.
• In this e 8 neutrons, some stable, nonradioactive isotopes are compared with some radioactive ones.

• An unstable nucleus can be formed by emitting radiation.

• A nucleus has two protons and two neutrons.
• An alpha particle has a mass number of 4, an atomic number of 2 and a charge of 2.
• The Greek letter alpha is the symbol for an alpha particle, except that the charge is not included.

• Zeros are used to show that a gamma ray has no mass or charge.

• An alpha particle has two protons and two neutrons.

• Write the symbol for the type of radiation that has a mass number of zero and a 1+ charge.

• When a molecule is hit by radiation, electrons may be knocked away.

• The cells that are most sensitive to radiation are those that are undergoing rapid division, which include the bone marrow, skin, reproductive organs, and intestinal lining.
• Cells that have been damaged may not be able to produce needed materials.
• Red blood cells may not be produced if the bone marrow is damaged by radiation.
• Birth defects can be caused by damaged sperm cells, ova, or the cells of a fetus.

• The cells of the nerves, muscles, liver, and adult bones are not as sensitive to different depths.

• Cancer cells are an example of rapidly dividing cells.
• Large amounts of radiation are used to destroy cancer cells.
• The normal tissue surrounding cancer cells is less damaged by radiation.

• Radiation may cause diseases.

• Nuclear medicine technologists, chemists, doctors, and nurses are required to use proper radiation protection.
• Alpha particles, which have the largest mass and charge of the radiation particles, travel only a few centimeters in the air before they collide with air molecules.
• There is a piece of paper, clothing and skin that protects us against alpha particles.
• Lab coats and gloves will protect you.
• If alpha particles are given off, they can cause serious internal damage.

• Alpha particles travel as much as several meters through the air, while the Beta particles move at a very small mass.
• They can penetrate up to 5mm into body tissue through paper.
• The surface of the skin can be burned, but the particles do not travel far enough to reach the internal organs.
• Lab coats and gloves are needed to protect the skin.

• Many materials, including body tissues, are affected by the rays.
• Exposure to the rays can be dangerous.
• Lead or concrete will stop them.
• The shielding used for the injections of radioactive materials is made of lead or plastic.

• Medical personnel wearing protective clothing and gloves stand behind a shield, keeping them away from the hands and body, when working with radioactive materials.
• In a nuclear pharmacy, shielding materials are made.

• The properties of radiation and shielding are required.

• If you work in a nuclear medicine facility where radioactive materials are present, try to keep the time you spend in a radioactive area to a minimum.
• If you stay in a radioactive area twice as long, you will get twice as much radiation.

• The lower Try Practice Problems 5.11 show the intensity of radiation received.
• If you double your distance from the radiation source, the intensity of the radiation drops to one-fourth of its previous value.

• Define the type of particle or radiation for each of the three.