For example, isochron methods do not assume any particular concentration of the daughter isotope in the original sample, but calculate that concentration based on other measurements.

The reliability of that calculation will in turn depend on other conditions.

Particle Location Charge Approximate mass Proton Nucleus 1 1 u Neutron Nucleus 0 1 u Electron Orbitals 1– 0 u 1. Several types of nuclear decay can be explored with the Nuclear Decay Gizmo™. Gamma rays are energetic electromagnetic waves; they are often emitted in nuclear decay. The boxes on the right represent the daughter product—the atom produced by radioactive decay—and the emitted alpha particle. In the top left box, write the mass number of the daughter product and press “Enter” on your keyboard. After filling in the boxes in the Gizmo, write the completed equation below: D. Practice: Click Reset, turn off Show equation, and select Polonium. Select Electron capture, and make sure Tungsten is selected. How will electron capture affect the atomic number and mass number of the atom? Calculate: Note that in this equation the particle is absorbed, rather than emitted. Fill in the electron capture equations for gold-195 and neodymium-141 in the spaces below. Name: ______________________________________ Date: ________________________ Part II – Half-life Vocabulary: daughter atom, decay, Geiger counter, half-life, isotope, neutron, radiation, radioactive, radiometric dating Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. If so, what do you hear while the popcorn is in the microwave? If you turn the microwave on for two minutes, is the rate of popping always the same, or does it change? Gizmo Warm-up Like an unpopped kernel in the microwave, a radioactive atom can change at any time. Activity A: Decay curves Get the Gizmo ready: • Click Reset ( ). The students are challenged to a Sherlock Holmes mystery in which they construct their own decay curves of melting ice to determine time zero.

In the process, the analogies to radiometric dating and some elementary thermodynamics are explained.

If the half-life is 47 years, how old is the material? Apply: Use the Gizmo to find the half-life of Isotope B. Print out this document and turn it in with this sheet. Explore: Use the Gizmo to explore whether the number of atoms present affects the half-life that you measure. Extend your thinking: The slow decay of radioactive materials can be used to find the age of rocks, fossils, and archaeological artifacts.

In a process called radiometric dating, scientists measure the proportions of radioactive atoms and daughter atoms in an object to determine its age.

In the Gizmo, select User chooses half-life and Theoretical decay.

Set the Half-life to 6 seconds (to represent 6,000 years) and the Number of atoms to 100.Name: ______________________________________ Date: ________________________ Lab 8 – Radiometric Dating Part I – Nuclear Decay Vocabulary: alpha particle, atomic number, beta particle, daughter product, gamma ray, isotope, mass number, nuclear decay, positron, radioactive, subatomic particle Prior Knowledge Questions (Do these BEFORE using the Gizmo.) The chart below gives the locations, charges, and approximate masses of three subatomic particles. Gizmo Warm-up While most atoms are stable, some are radioactive, which means that they have a tendency to undergo spontaneous nuclear decay.The approximate mass of each particle is given in universal mass units (u). The atomic number of an element is equal to the number of protons in each atom of the element. The decay of radioactive atoms generally results in the emission of particles and/or energy. Besides the alpha particle, what else is emitted from the nucleus during alpha decay? What you see is an equation that shows the original uranium atom on the left. In the bottom left box, write the atomic number of the daughter product and press “Enter.” What is this number? In the next set of boxes, enter the mass number and atomic number of the alpha particle, which has the same composition as the nucleus of a helium (He) atom. What happened to the proton after absorbing an electron? What is the mass number and charge of the absorbed electron? Predict: During electron capture, an electron is absorbed into the nucleus, causing a proton to transform into a neutron. Think and discuss: What do electron capture and positron emission have in common? Is the rate of decay fastest at the beginning, middle, or end of the process?The procedure, however, is difficult, and many tests have shown that it can be inaccurate, and it is at times not even considered reliable by mainstream scientists.It is impossible to measure the age of something, except to time it as it actually occurs, so radioactive dating methods calculate the age, based on (i) measurements of quantities of specified materials, (ii) measurements of decay rates, and (iii) assumptions about the history of the sample.Description Age (years) Egyptian papyrus with 63% of its original carbon-14 atoms Aboriginal charcoal with 22% of its original carbon-14 atoms.

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