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Isotopes

Isotopes. atoms of a given element that differ in the number of neutrons. …and consequently in mass. Working with Atomic Notation. Chemical Symbol. A z X. Atomic Mass (of Isotope). Atomic Number. Example #1. Chemical Symbol. 12 6 C. Atomic Mass (of Isotope). Atomic Number.

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Isotopes

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  1. Isotopes atoms of a given element that differ in the number of neutrons …and consequently in mass.

  2. Working with Atomic Notation Chemical Symbol AzX Atomic Mass (of Isotope) Atomic Number

  3. Example #1 Chemical Symbol 126C Atomic Mass (of Isotope) AtomicNumber

  4. Example #2 Chemical Symbol 136C Atomic Mass (of Isotope) Atomic Number

  5. Example #3 Chemical Symbol 146C Atomic Mass (of Isotope) Atomic Number

  6. Some isotopes of carbon 126C 136C 146C

  7. 10 Ne Neon 20.1797 47 Ag Silver 107.8682 3 Li Lithium 6.941 11 Na Sodium 22.98977

  8. Various ways of identifying Isotopes • Using atomic notation, Example: 126 C or simply 12C • Using the mass notation. • Example:Carbon-12 or C-12 • (read “carbon twelve” or “C twelve”)

  9. SomeIsotopes of Carbon

  10. Another example of isotopes 11H 21H 31H or H-1 H-2 H-3

  11. The Isotopes of Hydrogen

  12. Figure #1 Figure #2 Figure #3 p+ = no = e- = p+ = no = e- = p+ = no = e- =

  13. Isotopes atoms of a given element that differ in the number of neutrons …and consequently in mass.

  14. Why are masses on the periodic table usually expressed as decimal numbers? • masses on the table are weightedaverages of all known isotopes of the element of interest

  15. It is not possible to determine how many different isotopes exist by looking at the periodic table. • It is not possible to determine the frequency of various nuclides by looking at the periodic table. Keep in mind:

  16. The following does not occur in nature! 11Hoccurrence 33.3% 21H occurrence 33.3% 31H occurrence 33.3%

  17. The following does occur in nature! 11H occurrence 99.98% 21H occurrence 0.0156% 31Hoccurrence 0.0044%

  18. Imagine having 10,000 H atoms another way of looking at it: 11H occurrence 9,998 21H occurrence 1.56 31Hoccurrence 0.44

  19. That means the weighted average is: 11H 1 x 0.9998 = 0.9998 21H 2 x 0.00156 = 0.00312 31H 3 x 0.00004 = 0.00012 Weighted Average (0.9998 + 0.00312 + 0.00012)  1.01

  20. Zn has 5 naturally occurring isotopes 6430Znoccurrence 6630Znoccurrence 6730Znoccurrence 6830Znoccurrence 7030Znoccurrence

  21. Zn has 5 naturally occurring isotopes 6430Znoccurrence 49 % 6630Znoccurrence ~28 % 6730Znoccurrence ~4% 6830Znoccurrence ~18% 7030Znoccurrence ~1%

  22. Zn has 5 naturally occurring isotopes 65.39 6430Zn49 % 6630Zn~28 % 6730Zn~4% 6830Zn~18% 7030Zn~1%

  23. stable means “longest living” (parenthesis)on the Periodic Table indicate the most stable isotope Parenthesis also suggest the element of interest is radioactive.

  24. Review problem #1Represent the following using atomic notation. 92 U Uranium 238.0289

  25. Review problem #2Represent the following using mass notation. 10 Ne Neon 20.1797

  26. Review problem #3If the atom described below had 2 naturally occurring isotopes, which of the 2 would have a greater frequency of occurrence? Express your answer in atomic and mass notation. 3 Li Lithium 6.941

  27. Review problem #4How many total subatomic particles are in the following “neutral” atoms of Fe-55 and Fe-57?

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