Certain elements spontaneously release energy and particles of matter The number of neutrons vary in isotopes of the same element making little difference chemically but the nuclear properties of the isotopes may vary a great deal Atoms with too many neutrons are unstable which may decay (a natural process called radioactivity wherein the energy and particles emitted are nuclear radiation) Health issues 1) this ionizing radiation can produce charged ions in materials that it strikes; can produce changes in living tissues (a potential health hazard) 2) extreme case = fatal, lower levels may cause changes in enough cells to induce sickness, cause a slightly increased incidence of cancer, or have developmental effects on unborn children 3) Radiation injuries: hair loss and skin lesions, localized injuries similar to burns (normally to hands) 4) Radiation sickness: nausea, vomiting, diarrhea, malaise, hemorrhage and lowering of the body's resistance against disease and infection, if serious enough = death 5) Man-made radiation sources: diagnostic X-rays, radiotherapy x-rays, television tubes, luminous watch dials, radioactive waste products Units of measure:
Natural
Radioactivity a)
release of alpha, beta, and gamma radiation along with spontaneous fission
(breaking up of a nucleus into 2 large chunks with neutrons usually given
off c) beta particles beta particles --> negatively charged (-1) particle very similar to electron, travels somewhat faster d)
gamma radiation -X rays (from electron excitation) and gamma rays
(from nuclear excitation) can only be stopped by several inches of lead or
a foot of concrete gamma radiation --> as radiation, has no charge or mass but is energy and travels at speed of light, travels as photons (X-rays that come from electron excitation or gamma rays from nuclear excitation) Radioactivity in bombs and power plants: a)
if enough mass (called the critical
mass) of the isotope of uranium-235 is simply placed together it will
produce an uncontrolled chain reaction in less than a millionth of a
second. A
chain reaction is when one atom fissions and the products cause
the fission of additional atoms. If the chain reaction is uncontrolled, it
is called an atomic bomb Decay schemes alpha decay - radioactive nucleus that decays by giving off an alpha particle loses 2 protons and 2 neutrons. The atomic number is reduced by 2 and the atomic mass by 4. radium-226 à alpha + _____________ + energy beta decay - a radioactive nucleus that decays by giving off a beta particle loses an electron from the decay of a neutron into a proton, electron, anti-neutrino. The atomic number is thus increased by 1. The atomic mass stays the same.thorium-234 à beta + _____________ + energy electron capture - electron capture changes the nucleus by adding an electron from the innermost electron shell. This electron from the electron cloud combines with a proton to form a neutron. The atomic number is reduced by 1. The atomic mass stays the same. potassium-40 + electron capture à ________________ |
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