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Sub atomic heavyweights

Sub atomic heavyweights. Isotopes. ChemCatalyst. A chemist investigating a sample of lithium found that some atoms have a lower mass than other atoms. The chemist determined that the structures of the two types of atoms would be similar to the two drawings below. (cont.).

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Sub atomic heavyweights

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  1. Sub atomic heavyweights Isotopes

  2. ChemCatalyst A chemist investigating a sample of lithium found that some atoms have a lower mass than other atoms. The chemist determined that the structures of the two types of atoms would be similar to the two drawings below. (cont.) Unit 1 • Investigation III

  3. What is different about the two atoms? What is the atomic number of each atom? What is the mass number of each atom? Do you think they are both lithium atoms? Why or why not? (cont.) Unit 1 • Investigation III

  4. The Big Question How do isotopes of an atom account for the atomic weight of an element? Unit 1 • Investigation III

  5. You will be able to: Predict the isotopes of an element. Unit 1 • Investigation III

  6. Subatomic Heavyweights Work with a partner to complete the chart and compare answers to the questions in the handout

  7. WHAT IS AN ISOTOPE?

  8. Isotopes Atoms of the same element that have different numbers of neutrons They are all atoms of the same element Some values are more common (stable) than others

  9. Isotope Variations in the number of neutrons in atoms of a specific element Ex: Most hydrogen atoms have no neutrons. But a rare form of hydrogen atoms will have a neutron

  10. HOW TO WRITE THE NAME OF AN ISOTOPE

  11. Isotope names Two ways 1st: list the name or symbol of the element and the atomic mass of the isotope: Ex Uranium-237, U-238 • Write symbol of element and place the atomic mass on top and the atomic number below Ex 12 C 6

  12. Activity Purpose: In this lesson you will investigate isotopes and how they affect atomic weight. (cont.) Unit 1 • Investigation III

  13. (cont.) (cont.) Unit 1 • Investigation III

  14. (cont.) Unit 1 • Investigation III

  15. Atomic weight The weighted average of the atomic masses of different isotopes taking into account their abundance

  16. Questions for section Label sketches in question 1 How do you average values?

  17. Answers to lab questions Fill in chart 2 different isotopes: Boron-10, Boron-11 2 atoms of Boron-10, 8 atoms of Boron-11 10, 11 amu, add protons and neutrons (10+11+11+11+11+10+11+11+11+11)/10 = 10.80 amu 10.80 compared to 10.81

  18. More answers to lab questions 6a) 2 different isotopes 6b) 20 Boron-10 and 80 Boron-11 6c) 20%, 80%

  19. Even more answers to lab questions 8) 3 isotopes 9) Argon-40 is the most common 10) 4 neutrons, because Lithium-7 is most common isotope

  20. Making Sense Explain why the atomic weights listed in the periodic table are not usually whole numbers. Unit 1 • Investigation III

  21. While the element iron is defined as being made up of neutral atoms with 26 protons and 26 electrons, not every iron atom has the same number of neutrons. Atoms that have the same number of protons but different numbers of neutrons are called isotopes. Notes (cont.) Unit 1 • Investigation III

  22. What we call the atomic weight on the periodic table is actually the average atomic mass of that element’s naturally occurring isotopes. Isotopes have similar chemical properties in that they combine with other elements to form similar compounds. Notes(cont.) (cont.) Unit 1 • Investigation III

  23. Atomic Weight is the weighted average of the atomic masses of different isotopes taking into account their abundance. (cont.) (cont.) Unit 1 • Investigation III

  24. (cont.) Unit 1 • Investigation III

  25. If you finish early Cu Has 2 naturally occurring isotopes 69% with 34 neutrons, 31% with 36 neutrons Calculate average atomic mass of Cu

  26. Check in Predict the isotopes of Carbon, C. Which isotope is more abundant? How do you know?

  27. Wrap-Up Elements may have anywhere from 2 to 10 naturally occurring isotopes. The atomic weight of an element listed on the periodic table is actually the average mass of the naturally occurring isotopes of that element. Isotopes have the same number of protons and electrons, but different numbers of neutrons. (cont.) Unit 1 • Investigation III

  28. Isotopes of a single element exhibit similar properties in that they form similar compounds. Isotopes are referred to by their mass numbers. (cont.) Unit 1 • Investigation III

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