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36 1 Chemistry 52 Chapter 18 RADIOACTIVITY
· The discovery o f radioactivit y can be attributed to several scient ists. Wilhelm Roentgen discovered Xrays in 1895 and shortly after that Henri Becquerel observed radioactive behavior while experiment ing with salts o f uranium. However, the term radioactivit y was first coined by Marie Curie in 1898.
· Radioactivity is the spontaneous emissio n of particles and/or rays from the nucleus of an atom. Nuclides are said to be either stable (nonradioactive) or unstable (radioact ive).
· All elements having an atomic number greater than 83 (bismuth) have unstable nuclei, which undergo spontaneous decay (disintegration), and are therefore radioactive.
· These elements can undergo one of three different kinds of decay called a (alpha), b (beta) and g (gamma). When decaying, the original nucleus (A) changes into another nucleus (B) and gives off radiat ion (b) according to the general equation shown below: A ¾ ¾
® B + b Parent...
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