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Electrons in Atoms

Explore the electron configurations in atoms and the unanswered questions surrounding their arrangement. Learn about the wave-like properties of light and the electromagnetic radiation it exhibits. Understand the quantum model and its implications on electron behavior. Discover the particle nature of light and the quantum leap phenomenon. Gain insights on electron configurations using the quantum mechanical model and its rules. Explore the photoelectric effect and atomic emission spectra.

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Electrons in Atoms

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  1. Electrons in Atoms Electron Configurations

  2. The Nuclear Atom & Unanswered Questions • Rutherford • Model did not show how electrons occupy space around nucleus. • Did not answer why electrons are not pulled into atom’s “+” charged nucleus.

  3. Light • Certain elements emit visible light when heated into a flame. • This chemical behavior is related to the arrangement of the electrons in its atom.

  4. Wave-like Properties of Light • Examples include ultraviolet, infrared light, microwaves, & radio waves. • These are known as Electromagnetic Radiation

  5. Electromagnetic Radiation • Form of energy that exhibits wavelike behavior as it travels through space. • Moves through a vacuum at a constant speed of 2.998 x 108 m/s • Measurable wave properties: wavelength (λ) and frequency (v)

  6. Quantum Model • Theory that states that electrons have wavelike properties. • Electrons are thought of waves confined to the space around the atomic nucleus. The frequency of the electrons is based on the type of element.

  7. Wave Label amplitude, wavelength, and frequency.

  8. How has the frequency & wavelength changed?

  9. How has the frequency & wavelength changed? The lower the frequency, the _________________ the wavelength. The higher the frequency, the _________________ the wavelength

  10. Equations: c= λv E = hv E = h c/λ h = Planck’s Constant= 6.626 x 10-34 J*s C = speed of light (2.998 x 108 m/s) λ = wavelength V = frequency

  11. Example: • What is the wavelength of electromagnetic radiation having a frequency of 5.00 x 1012 Hz?

  12. Example #2 • What is the frequency of electromagnetic radiation having a wavelength of 3.33 x 10-8 m?

  13. Particle Nature of Light- The Quantum Model • Quantum= minimal amount of energy required to move an electron from its present energy level to the next higher one.

  14. Particle Nature of Light- The Quantum Model • Quantum Leap= abrupt change of electrons going from present energy level to the next higher one. • (Think about photosynthesis!!)

  15. Particle Nature of Light- The Quantum Model • Quantum Mechanical Model (1926) • Based on math with probability • Fuzzy cloud of electrons • Principle Quantum Number (n) • n = 1 Lowest Energy Level (1s) • n = 2 Next Higher Energy Level (2s2p)

  16. Sublevels Orbitals Shape s 1 spherical p 3 dumb bell d 5 clover leaf f 7 too hard to visualize

  17. 8 x 8 grid

  18. Rules for Electron Configurations • Aufbau Principle= electrons enter orbitals of lowest energy first • Pauli Exclusion Principle= 2 electrons in one orbital must have opposite spins (directions) • Hund’s Rule= when you have a sublevel with more than 1 orbital, must have 1 electron in each orbital before you can double up.

  19. Photoelectric Effect • Solar powered items (convert light into electrical energy) • Photoelectrons • Wave model does NOT explain this! • 1905- Einstein stated that electromagnetic radiation has both wavelike and particle like natures. (Stream of bundles of E called photons)

  20. Reading: • Read and take notes on your own on the Atomic Emission Spectra (p125-126)

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