1 / 8

Honors Chemistry Unit 3 - Electrons

Honors Chemistry Unit 3 - Electrons. Lesson 4 – The Bohr Model of the Atom Book Section: 4-1 Do Now: Prepare for Quiz 3-2 Objective: SWBAT calculate the energies of specific colors of light. Agenda: Quiz, Lesson, Videos, Element of the Day. Line Spectra.

nina-foreman
Download Presentation

Honors Chemistry Unit 3 - Electrons

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. Honors ChemistryUnit 3 - Electrons Lesson 4 – The Bohr Model of the Atom Book Section: 4-1 Do Now: Prepare for Quiz 3-2 Objective: SWBAT calculate the energies of specific colors of light. Agenda: Quiz, Lesson, Videos, Element of the Day

  2. Line Spectra • When we excite the electrons in hydrogen gas and view the emitted light through a spectroscope/prism, the following pattern emerges:

  3. Line Spectra • Instead of a full spectrum of light, only four distinct lines are shown! • This means that electrons in the hydrogen atom have only certain places that they can be, and they are not free to move throughout the hydrogen atom, because otherwise we would see the full spectrum.

  4. The Bohr Model • Danish physicist Niels Bohr proposed a model of the atom that fit the line spectra. • Bohr postulated that electrons could only be in certain energy levels, and that when an electron fell from a higher to a lower energy level, the difference in energy came out as light. • The diagram shows an electron falling from the third to the second energy level. • VIDEO: I Am Furious Yellow • VIDEO: Niels Bohr

  5. Energy of Emitted Photons • Based on what happens to the light, we can tell the direction of the electron. • If light is absorbed, electrons are excited from a lower to higher energy level. • If light is emitted, electrons relax from a higher to lower energy level. • The energy of the light tells us the difference in energy between the energy levels. • If ΔE is positive, light is absorbed. • If ΔE is negative, light is emitted.

  6. Energy of Emitted Photons • As a general rule… • IR light is emitted if the electron relaxes to the n = 3 energy level. • Visible light if it relaxes to n = 2 • UV light if it relaxes to n = 1.

  7. Practice • An electron moves from the n = 4 to n = 2 energy level in a hydrogen atom. (E4 = -1.36 x 10-19 J, E2 = -5.45 x 10-19 J) • Is light emitted or absorbed? • What is the energy of the light? • What is the wavelength of the light in meters? • What is the wavelength of the light in nanometers? • What type of light (UV, vis, IR) is absorbed or emitted?

  8. HW 3-4: #30-33 • Next Week: • Tuesday: The Quantum Mechanical Model, Quiz 3-4 • Wednesday: No Class • Thursday: Electron Configurations, Quiz 3-5 • Friday: Orbital Box Diagrams, Quiz 3-6 • Likely Unit 3 Test Date: Tuesday, October 19

More Related