Transcript Catalyst
Catalyst • 1. Write down Dalton’s postulate that was proven wrong by the existence of isotopes. • 2. How does the existence of isotopes disprove this component of Dalton’s atomic theory? End Marie Curie! • Marie Klodowska Curie discovered the mysterious element radium. It opened the door to deep changes in the way scientists think about matter and energy. • Radioactivity had nothing to do with whether the material was solid or powdered, dry or wet, pure or combined with other chemical elements. If you had a certain amount of uranium—a certain number of uranium atoms—then you got a certain intensity of radiation. Nothing else made a difference. Women in STEM • When the Nobel Prize for Physics was awarded to Pierre and Marie Curie in 1903, the great honor quickly changed their lives. Pierre was finally appointed to a professorship at the Sorbonne, and the university belatedly found funds for a laboratory for him. It also hired Marie—the first woman to win a Nobel Prize—as “laboratory chief.” Module 2.3 – Marie Curied Boar Meat Next Model in the Development of Atomic Theory: Curie ISOTOPES AND RADIOACTIVE DECAY Today’s Learning Targets • LT 2.3 – I can identify the number of protons as the atomic number and calculate average atomic mass on the periodic table using relative isotope abundance data. What are isotopes? I. Isotopes • Isotope – Atoms of the same element have different numbers of neutrons and thus have different atomic masses. How are isotopes and relative abundances related? II. Calculating Average Atomic Mass • In nature, we have various amounts of each isotope of an element • Therefore, we use the abundance to get a relative mass Relative Mass = (Isotope Abundance)(Isotope Mass) Average Atomic Mass=Relative MassIsotpe A +Relative MassIsotope B. . Class Example • Naturally occurring chlorine is 75.78% 35Cl and 24.22% 37Cl. Calculate the average atomic mass of chlorine. Table Talk • Three isotopes of silicon occur in nature, 92.23% is 28Si, 4.68% is 29Si, and 3.09% is 30Si. Calculate the average atomic mass of silicon. Stop and Jot • Only two isotopes of copper occur naturally 63Cu accounts for 69.17% and 30.83% is 65Cu. Calculate the average atomic mass of copper. Summarize! Use the following terms in your summary: • Isotope • Relative Abundance • Sum Learning Target Log Assessment • Go to letsgeddit and rate your current level of understanding for LT 2.2. Rate yourself 1 – 4. How does this connect to radioactive boars? Radioactive Boar Meat! • Make some radioactive boar burgers! • Good idea? Or nah? Online Simulator • Please open the two simulators on the computer and complete the simulator handout with a partner. What is radioactive decay? I. Radioactive Decay • Atoms can be unstable and breakdown • Radioactive Decay – The spontaneous breakdown of the nucleus into a smaller nucleus, accompanied by the release of particles, radiation, or both. What are the three types of decay? I. Alpha (α) Decay • Alpha Decay – When an atom splits its nucleus into: 1. A smaller nucleus and 2. A Helium atom (2 protons, 2 neutrons). • Observed often in very heavy atoms • Alpha particles on travel a few cm in air • Paper blocks alpha particles Alpha Radiation II. Beta (β) Decay • Some elements are unstable because their proton to neutron ratio is too large. • Beta decay converts neutrons to protons and releases an electron known as a beta particle neutron proton + β • Travel a few meters in the air • Metals provide a shield against beta radiation. Electron Beta Radiation III. Gamma (γ) Decay • Gamma rays are high energy waves that are released when nucleus goes from high energy state to low energy. • Gamma radiation is the most dangerous. It can lead to DNA mutations and cancers. • Gamma radiation requires thick pieces of lead/concrete in order to stop. Gamma Radiation Radiation Summary Type of Radiation Description Blocked by? Alpha (α) The spitting of a nucleus into a smaller nucleus and a He atom (alpha particle Blocked by paper Beta (β) Converts a neutron to a proton and an electron (beta particle) Blocked by metals Gamma (γ) High energy waves that are released by nucleus Blocked by lead Class Example • Label the following decay as alpha, beta or gamma decay 43 K 43 Ca + electron 19 20 Table Talk • Label the following decay as alpha, beta or gamma decay 210 Po 206 Pb + 4 He 84 82 2 Table Talk • Complete the following reaction if it undergoes beta decay: 14 N ______ + _______ 7 SUMMARIZE! Use the following terms in your summary: • Alpha • Beta • Gamma • Decay • Radioactive Work Time • Work on practice for the next 10 minutes. Learning Target Log Assessment • Rate your current level of understanding of LT Rate yourself 1 – 4. Exit Slip 1. Naturally occurring chlorine is 75.78% 35Cl and 24.22% 37Cl. Calculate the average atomic mass of chlorine. 2. What is gamma decay? What will stop gamma radiation? 3. What type of decay is shown below: 231 Pa 227 Ac + 4 He 91 89 2 Learning Target Log Assessment • Rate your current level of understanding of LT. Rate yourself 1 – 4. Closing Time • Practice due Monday/Tuesday • Test next Tuesday/Wednesday