Lab 5 – Emission Spectra

1. Lab 5 – Emission Spectra

2. According to Kepler’s 1st Law a planet orbits the sun in an elliptical orbit. Where is the sun located? • On the major axis in the exact center of the ellipse. • On the major axis at one of the focus points. • On the minor axis halfway between the center and the orbit. • At the perihelion point on the orbit • At the aphelion point on the orbit

3. Every chemical element has a unique spectral signature. • True • False • A few elements actually have identical emission lines.

4. Color Wavelength Light Waves Wavelength () Red Light – Longer Wavelength, Lower Energy Blue Light – Shorter Wavelength, Higher Energy

6. Narrow beam of light White Light Source Spectroscope Screen PrismorDiffraction Grating -e narrow slit Spectrum

7. Kirchhoff’s First Law • Hot, dense gases or solids produce a continuous spectrum. • Example: Light bulb filament Continuous Spectrum

8. Kirchhoff’s Second Law • Hot, rarefied gas produces an emission line spectrum. • Example: Neon sign Emission Line Spectrum

9. Kirchhoff’s Third Law • Cool gas in front of a continuous source of light produces an absorption line spectrum. • Example: The Sun Absorption Spectrum

10. Electric charge - Electrons + Protons Neutrons Nucleus protons/neutrons electrons Atoms +

11. Hydrogen Atom 5 Energy Levels 4 -e 434 nm 3 2 656 nm -e 1 -e +P 486 nm 410 nm -e -e 400 nm 700 nm

12. Aluminum Argon Calcium Carbon Helium Hydrogen Iron Krypton Magnesium Neon Nitrogen Oxygen Sodium Sulfur Xenon

13. How to Excite an Atom Absorption of Light 400 nm 700 nm White Light Source Screen Prism -e Hydrogen Gas

14. How to Excite an Atom 4 3 400 nm 700 2 White Light Source 1 +P 656 nm Absorption of aPhoton Hydrogen Atom -e -e

15. How to Excite an Atom 4 3 2 UV 1 +P Collision with Another Particle Hydrogen Atom -e -e -e -e

16. 400 nm 500 nm 600 nm 700 nm A B C Which one of the following is an emission spectra?

17. When an electron in an atom moves from a high energy level to a lower energy level • a photon of light is emitted. • a photon of light is absorbed. • the atom becomes ionized. • the atom gains a proton.

18. The End

19. 400 nm 500 nm 600 nm 700 nm 400 nm 500 nm 600 nm 700 nm

20. 700 nm 400 nm