1 / 71

Understanding Atomic Structure: The Discovery of Electrons and Nuclides

This comprehensive overview covers the key milestones in atomic theory, including Thomson's discovery of the electron, evidenced by the cathode ray tube experiments, and the subsequent development of the Plum Pudding and Planetary models. The text delves into Millikan's oil drop experiment, which quantified the electron's charge and mass, and explores Rutherford's Gold Foil experiment that led to the identification of the atomic nucleus. Additionally, it addresses concepts of isotopes, nuclear stability, and decay types, providing fundamental insights into atomic structure.

howie
Télécharger la présentation

Understanding Atomic Structure: The Discovery of Electrons and Nuclides

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What is simplified in this picture?

  2. TheThompson: Discovery of the Electronthe Electron (Thomson) • Cathode Ray Tube • Charged particles produced (affected by magnetic field)

  3. Concluded that atom must have positive and negative parts • Electron – negative part of the atom • Only knew the e/m ratio • Plum Pudding Model

  4. Charge and Mass of the Electron (Millikan) • Oil drop experiment • Determines charge on electron (uses electric field to counteract gravity) • Quantized • e = 1.602 X 10-19 C • m = 9.11 X 10-31 kg

  5. The Nucleus (Rutherford) • Gold Foil Experiment • Discovers nucleus (disproves Plum Pudding Model) • Planetary Model

  6. Atoms:Basic Facts Three particles

  7. Photo of a single Barium atom

  8. Atoms:Basic Facts • Size – Measured in Angstroms 1 A = 1 X 10-10 m 1 Cl atom = 2.0 A 5 million Cl atoms can be lined up in 1 mm.

  9. Atoms:Basic Facts • Mass – grams/mole H = 1.00794 grams/1 mole 1.00794 g/6.022 X 1023 atoms C = 12 g/mol

  10. Isotopes • Isotopes – Atoms with the same # of protons, but different # of neutrons Copper-63 29 p 34 n Copper-65 29 p 36 n 2. Atomic Mass –weighted average of all the isotopes

  11. Ions • Cation – Positive Ion • Anion – Negative Ion • Review Common Charges

  12. Stable vs. Unstable Nuclei Nuclear Changes • Most nuclei are stable – do not change • Some nuclei are unstable (radioactive) • Change into a different nucleus (decay) • Spontaneous process – happens naturally, by itself • Releases radiation Only nuclear reactions can change a nucleus. No chemical process can

  13. Radium  Radon + Radiation Decay -New element and alpha, beta, or gamma -lost mass becomes kinetic energy

  14. Types of Nuclear Radiation 2 p+ 2 n e-

  15. What Stops Radiation Al Foil Wood Lead. Iron, Concrete Paper Alpha () Beta () Gamma ()

  16. Decay Equations Alpha Decay 23892U 42He + 23490Th Beta Decay 23490Th0-1e + 23491Pa

  17. Decay Equations Gamma Decay Occurs with alpha and beta decay No change in atomic mass (gamma radiation has no mass 00)

  18. Decay: Ex 1 What product is formed when radium-226 undergoes alpha decay? 22688Ra 42He +

  19. Decay: Ex 2 What element undergoes alpha decay to form lead-208? 42He + 20882Pb

  20. Decay: Ex 3 What isotope is produced when thorium-231 beta decays? 23190Th 0-1e +

  21. Write the equation that describes oxygen-15 undergoing positron emission.

  22. Which nuclei are radioactive (unstable) • All elements have at least one radioactive isotope • All isotopes of elements heavier than Lead (82) 82 Pb 207.2 At least one radioactive isotope All isotopes are radioactive

  23. Transmutation • Rutherford(1919) – First successful alchemist 147N + 42He 178O + 11H • Modern methods • Particle Accelerators (Cyclotrons) • Use neutrons or other elements (creation of transuranium elements)

  24. Periodic Table • Dmitri Mendeleev – 1869 • Used atomic mass (modern is by atomic #) • Period – Across • Group – Down • Metals Non-Metals Metalloids - Semiconductors

  25. Periodic Table Group 1 Alkali metals Group 2 Alkaline earth metals Transition Metals Group 7 Halogens Group 8 Noble Gases Lanthanides Actinides Discuss placement of Lanth/Act

  26. Average Atomic Mass Atomic Mass – Weighted Average of all the isotopes

  27. Average Atomic Mass Calculate the ave atomic mass of Boron if it exists as 19.90% Boron-10 (10.013 g/mol) and 80.10% B-11 (11.009 g/mol)? (Ans: 10.811 g/mol)

  28. Mixing Elements Ionic = Metal + Non-metal (NaCl) Molecular = Non + Non (CH4) Alloy = Metal + Metal • Stainless steel (Fe/Cr) • Brass (Cu/Zn) • Bronze (Cu/Sn)

  29. Ionic vs. Molecular

  30. Ionic Solids

  31. Ionic vs. Molecular Ionic or molecular? HCl CO2 VO3 H2O BaF2

  32. What ionic compound would form between: Ba and Cl Ba and Te Al and S Fe3+ and O Fe2+ and O

  33. Naming Ionics • Binary Compounds Gr I and Gr II metals (and Aluminum) NaCl BaO Al2O3 magnesium bromide aluminum sulfide potassium oxide

  34. Naming Ionics • Compounds with Polyatomics Sodium hydroxide Sodium carbonate Aluminum Sulfate NaNO3 Ca(OH)2 (NH4)3PO4

  35. Mixed Examples Magnesium Sulfide Magnesium Sulfite Magnesium Sulfate Lithium Phosphide Lithium Phosphate Ba(ClO3)2 BaCl2

More Related