1. The Electromagnetic Spectrum and Light

2. Wavelength - The distance between two consecutive peaks of a wave.

3. Frequency - The number of cycles in a certain period of time… measured in cycles per second, or Hertz (Hz). 1Hz = 1/sec = 1 sec -1

4. c =ƒ*λ C = speed of light, a constant (3.00 x 10 8 m/s) ƒ = frequency, in units of hertz (hz, sec -1 ) λ = wavelength, in meters Electromagnetic radiation propagates through space as a wave moving at the speed of light.

5. Just how much of the spectrum is visible? Let’s Check this out! Electromagnetic spectrum video

6. Types of electromagnetic radiation:

7. Ultraviolet Rays

8. E = h*ƒ E = Energy, in units of Joules (kg·m 2 /s 2 ) h = Planck’s constant (6.626 x 10 -34 J·s) ƒ = frequency, in units of hertz (hz, sec -1 ) The energy (E ) of electromagnetic radiation is directly proportional to the frequency (ƒ) of the radiation.

9. Long Wavelength = Low Frequency = Low ENERGY Short Wavelength = High Frequency = High ENERGY Wavelength Table

10. …produces all of the colors in a continuous spectrum Spectroscopic analysis of the visible spectrum…

11. …produces a “bright line” spectrum Spectroscopic analysis of the hydrogen spectrum…

12. Atomic Spectra When atoms absorb energy electrons move into higher energy levels… …these electrons lose energy by emitting light when they return to lower energy levels. No two elements have the same emission spectrum

14. Iron Hydrogen

16. Ground State: the lowest possible energy of the electron Excitation of the electron by absorbing energy raises it from the ground state to an excited state A quantum of energy (in the form of light) is emitted when the electron drops back to a lower energy level. The light emitted by an electron moving from a higher to a lower energy level has a frequency directly proportional to the energy change of the electron.

19. electron elevates to another level. Quantum of energy hits electron As electron falls back to ground state, light is emitted

20. Animation of excitation and emission Animation of absorption and emmision

22. Electron transitions involve jumps of definite amounts of energy. This produces bands of light with definite wavelengths.

24. So what does this do to our model of the atom? Tells us that there are discrete Energy levels in all atoms, called the Principle Energy level (sometimes called shells) as noted by “n”. Each atom has a specific ability to give off certain amounts of light, like a finger print. Each energy level can only contain a certain number of electrons. – These energy levels are further sub-divided into sub- energy levels – All of these levels are E levels and are reflected on the period table. How?

26. Flame Tests