1. Electrons in Atoms

2. Wave Behavior of Light Day 1

3. Parts of a Wave wavelength – the length of one wave Frequency - number of waves that pass a given point per second crest trough amplitude wavelength

4. Wave Nature of Light Electromagnetic radiation – form of energy that exhibits wave like behavior

5. c = νλ Where: C = speed of light (c = 3.0 x 10 8 m/s) C = speed of light (c = 3.0 x 10 8 m/s) ν = frequency ν = frequency λ = wavelength λ = wavelength speed of electromagnetic waves is always the same wavelength and frequency can change and are inversely related

6. Example What is the frequency of green light with a wavelength of 460 nm?

7. 7 In Bohr’s model when energy is added to an atom it causes electrons to move from its ground state (low energy level) to an excited state (higher energy level). Ground state Excited state Niels Bohr

8. 8 All electrons come down from their excited state and return to the ground state, eventually. When the electron falls back down to the ground state, the energy is given off as electromagnetic radiation! (light)

9. Particle Behavior of Light Day 2

10. Max Planck (1900) Matter gains or loses energy in small specific amounts called quanta His equation describes the relationship between energy and radiation (light) frequency

11. Albert Einstein (1905) Explained light rays as both wavelike and as a stream of particles This is known as the photoelectric effect He called these particles photons Photons – particle of EM radiation with zero mass and carries a quantum of energy Photons – particle of EM radiation with zero mass and carries a quantum of energy

12. Photoelectric Effect E quantum = h ∙ υ where E = energy υ = radiation’s frequency, υ = radiation’s frequency, h = Planck’s constant (6.626 x 10 -34 J∙s) h = Planck’s constant (6.626 x 10 -34 J∙s)

13. Example What is the frequency of light that has an energy of 2.0 × 10 -18 joules ? TWO STEP EXAMPLE What is the wavelength of a yellow light with an energy of 3.37 x 10 -19 J?

14. Hydrogen-Atom Line Emission Spectrum When light passes through a prism, it is separated into specific wavelengths. The pattern that are seen are different for every element.