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Nuclear Radiation & Transformations. Marie Curie. Marie Curie was a Polish scientist whose research led to many discoveries about radiation and radioactive elements. In 1934 she died from leukemia caused by her long-term exposure to radiation. Radioactivity.
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Marie Curie • Marie Curie was a Polish scientist whose research led to many discoveries about radiation and radioactive elements. In 1934 she died from leukemia caused by her long-term exposure to radiation.
Radioactivity • Marie Curie (1867-1934) and Pierre Curie (1859-1906) were able to show that rays emitted by uranium atoms caused fogging in photographic plates. • Marie Curie named the process by which materials give off such rays radioactivity. • The penetrating rays and particles emitted by a radioactive source are called radiation.
Radioactivity • In nuclear reactions, the nuclei of unstable isotopes, called radioisotopes, gain stability by undergoing changes. • An unstable nucleus releases energy by emitting radiation during the process of radioactive decay.
Types of Radiation • Alpha • Beta • Gamma
Alpha Radiation 4 4 He or α 2 2 • Nuclear Symbol: • Made of: • Mass: • Charge: 2 p+ and 2 n0 4 +2
Beta Radiation • An electron resulting from the breaking apart of a neutron in an atom is called a beta particle.
Beta Radiation 0 e 0 or β -1 -1 • Nuclear Symbol: • Made of: • Mass: • Charge: electrons (-) 0 -1
Gamma Radiation • Nuclear Symbol: • Made of: • Mass: • Charge: γ • Usually emitted along with alpha radiation or beta radiation. electromagnetic waves 0 0
Gamma-Ray Radiation Cobalt-60 Nickel-60
What stops alpha, beta, and gamma radiation? Alpha particles are the least penetrating. Gamma rays are the most penetrating.
Nuclear Stability and Decay • The stability of the nucleus determines the type of decay (alpha, beta, gamma) a radioisotope undergoes. • The protons in a nucleus want to repel against each other. • There is a strong force that holds the protons and neutrons together in the nucleus
What makes an atom radioactive? • When the strong nuclear force cannot hold the protons and neutrons together.
Which elements are unstable (radioactive)? • All nuclei with more than 83 protons (shade these in on the small periodic table) • However, many other nuclei with only a few protons are also radioactive
Transmutation Reactions • The conversion of an atom of one element to an atom of another element is called transmutation. • Transmutation can occur by radioactive decay. • Transmutation can also occur when particles bombard the nucleus of an atom.
Fission & Fusion BOTH: release A LOT of energy
Fission • A large nucleus is split apart. • Usually releases particles that perpetuate a chain reaction
Fission • A large nucleus is split apart. • Usually releases particles that perpetuate a chain reaction • Used to generate electricity and in nuclear weapons
Fusion • 2 small nuclei combine (fuse together) • Occurs at very high temperature and pressure • Occurs in the sun & other stars
Geiger Counter • Used to detect radioactive substances
Half-Life • HALF-LIFE is the time that it takes for 1/2 a sample to decay. • The rate of a nuclear transformation depends only on the “reactant” concentration.
Half-Life • The ratio of Carbon-14 to stable carbon in the remains of an organism changes in a predictable way that enables the archaeologist to obtain an estimate of its age. • Radiocarbon dating is used to determine the approximate age of a sample of matter.
