Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Standard Model wikipedia , lookup
ATLAS experiment wikipedia , lookup
Compact Muon Solenoid wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Electron scattering wikipedia , lookup
Nuclear structure wikipedia , lookup
ch3Video2.notebook December 19, 2014 Chapter 3 Video 2: Radioactivity Objectives: • be familiar with the terminology of radioactive decay • be able to write the nuclear symbol and charge for alpha and beta particles • be able to describe gamma decay • be able to compare the penetrating ability of alpha, beta and gamma radiation • be able to state the effects of alpha, beta and gamma decay on the nucleus of a radioactive atom • be able to state the definition of halflife of a radioactive atom Dec 173:36 PM 1 ch3Video2.notebook December 19, 2014 Radioactivity discovered Henri Becquerel Pierre & Marie Curie Radioactive Decay -• the spontaneous emission of energy and usually particles from an unstable nucleus to produce a more stable atom • when particles are emitted, the identity of the element changes. (transmutation) Daughter nuclide = new atom that is the result of a nuclear transmutation Jan 68:23 AM 2 ch3Video2.notebook December 19, 2014 Experimental determination of the nature of radioactivity Dec 171:16 PM 3 ch3Video2.notebook December 19, 2014 3 Types of Radioactive Decay Alpha Decay = emission of an alpha particle from the atom's nucleus Alpha Particle = a Helium nucleus Nuclear Symbol = Daughter nuclide is a different, lighter element (mass# decreases by 4) Beta Decay = emission of a beta particle from the atom's nucleus Beta Particle = an electron Nuclear Symbol = In the nucleus, a neutron becomes a proton and ejects an electron Daughter nuclide has the same mass, but one less neutron Gamma decay a highly energized nucleus emits energy (electromagnetic radiation, which is high energy light) to become more stable The Daughter nuclide is the same atom as the Parent There is no nuclear symbol for Gamma because it is NOT a particle, just energy. It is abbreviated using the Greek letter gamma = We will use the nuclear symbols for alpha and beta particles to write nuclear decay equations next class. Be sure you can write each of those symbols correctly. Jan 68:23 AM 4 ch3Video2.notebook December 19, 2014 beta decay Jan 510:31 AM 5 ch3Video2.notebook December 19, 2014 Half-life = t1/2 = the time for one half of a radioactive sample to decay and transmutate into a new, more stable atom Example: if t1/2 is 1 day, after 1 day, a sample of 1000 atoms will have transmutated, leaving only 500 atoms of the original isotope. After 2 days (2 half-lives), only 250 of the original isotopes will remain unchanged. Question: What fraction of the original sample remains unchanged after 4 half-lives? Jan 61:49 PM 6