1 / 20

The Element’s Fingerprint: Atomic Spectra

The Element’s Fingerprint: Atomic Spectra. Backgroun d Information: Diffraction Grating. D iffraction grating splits a light source into its components (light of various wavelengths and colors). Backgroun d Information: What is a spectroscope?.

mahon
Download Presentation

The Element’s Fingerprint: Atomic Spectra

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. The Element’s Fingerprint: Atomic Spectra

  2. Background Information: Diffraction Grating Diffraction grating splits a light source into its components (light of various wavelengthsand colors)

  3. Background Information: What is a spectroscope? A spectroscope contains a diffraction grating as well as a scale to measure the wavelengths of visible light.

  4. Review of some very important terms! Ground State Electrons – lowest energy of an electron (normal) Excited State Electrons – higher energy of electron (temporary)

  5. ELECTRON JUMPING DEMO

  6. WHEN AN ELECTRON ABSORBS ENERGY . . . When an electron absorbs energy (like heat from a flame or electrical energy!) it jumps to a higher energy shell—this is unstable! (EXAMPLE: An electron moves from shell 1 to shell 2) nucleus Electron moves from GROUND state to EXCITED state e- e-

  7. An e- releases energy when it goes from excited to ground state Energy is released in the form of light Visible colors = light energy released by “falling” electrons AN ELECTRON RELEASES ENERGY . . . Energy released = E2 – E1 nucleus e- e-

  8. Atomic Emission Spectrum • An atomic emission spectrum is: • What we see when we look into a spectroscope(through a diffraction grating). • A series of discrete “spectral” lines that are characteristic of the element • Each line corresponds to one exact frequency of light (amount of energy) emitted by the atom Helium line spectra

  9. Atomic Emission Spectrum Cont’d • Atomic spectra an be used to identify unknown elements • Much of the knowledge of the universe comes from studying the atomic spectra of stars

  10. How to see an atomic line spectrum:

  11. Hydrogen emission spectra: o

  12. Hydrogen emission spectra: How does Hydrogen give off multiple bands of light? • ANSWER: • Many hydrogen atoms (all with one electron) have electrons jumping up to a few different energy levels. • Then, they fall back down and release photons with wavelengths in the visible spectrum (violet, blue, cyan and red)

  13. Hydrogen emission spectra: Which bands are from high energy jumps, which are from low energy? • ANSWER: • High energy jumps: Violet and teal bands • Low energy jumps: Red band

  14. WRITE IT! Why do you think different elements have different atomic spectra?

  15. SHARE IT! Share your answer with your table group. Have the person closest to the large periodic table go first.

  16. Why are spectra unique? • Each element has a different number of electrons & protons • This makes energy levels in each element unique, and the possible energy jumps unique • Since energy jumps = colors emitted, each element emits unique colors of light

  17. What if there were NOT “quantized” energy levels? Infinite possible energy levels, infinite sizes of jumps, all colors produced

  18. What’s in the lightbulbs? • Mercury! • Is is dangerous? (see excerpt below from Popular Mechanics) • Why do CFLs require mercury to produce light?Compact fluorescent bulbs are made of glass tubes filled with gas and a small amount of mercury. CFLs produce light when the mercury molecules are excited by electricity running between two electrodes in the base of the bulb. The mercury emits ultraviolet light, which in turn excites the tube’s phosphor coating, leading it to emit visible light. • How much mercury is contained in a CFL?Each bulb contains an average of 5 milligrams of mercury, “which is just enough to cover a ballpoint pen tip,” says Leslie, associate director of the Lighting Research Center at Rensselaer. “Though it’s nothing to laugh at, unless you wipe up mercury [without gloves] and then lick your hand, you’re probably going to be okay.” • Why are incandescents less efficient than CFLs?Unlike compact fluorescents, incandescent bulbs produce light by heating the metal filament inside the bulb. When electricity passes through the filament, its temperature rises to 2,300 degrees Celsius, with the heat causing the filament to glow white-hot and emit light. But only 5 to 10 percent of that electricity is transformed into visible light. “In an incandescent bulb, much of the electricity is used for heat, which is not efficient,” Leslie says. “Fluorescent lights use electricity to do much more than heat a solid object.” • http://www.popularmechanics.com/blogs/home_journal_news/4217864.html

  19. Identify the element! HELIUM

  20. Identify the element! HYDROGEN

More Related