Wave & Particle Nature of Light

1. Wave & Particle Nature of Light EQ: How can an atom be a "particle" and a "wave" at the same time?

2. Why do heated objects emit only certain frequencies of light? • Temperature of an object is a measure of the average kinetic energy of its particles • As an object gets hotter, it possess a greater amount of energy and emits different colors of light • Different colors are due to different frequencies and wavelengths Quantum Concept

3. Ground vs. Excited States of e- • Ground State: Lowest energy e- configuration • Shown on Periodic Table • Innermost energy level fills first, then work outward Ground State vs. Excited State

4. Excited State: e- can move to a higher energy level without filling the lower energy level first • Do this by absorbing energy • Excited e- fall back to ground state by releasing energy Ground State vs. Excited State

5. Photon: Massless particle that carries a quantum of engergy. photon photon The SVP Universal Cosmology A Rosetta Stone for the New Science Paradigm

6. Elements give off different colors depending on the amount of energy released (how far the e- falls) Diagram

7. Neon – Ground vs. Excited State

8. German physicist Max Planck established that matter gains or loses energy in small amounts called quantum • Quantumis the minimum amount of energy that can be gained or lost by an atom. • Planck’s mathematical equation for his findings is Equantum= hv Quantum Concept

9. Ephoton= hv Equantum= Energy h = Planck’s constant (6.626 x 10-34 J s) v = Frequency *Note: Joule (J) is the unit of energy Quantum Concept

10. c = λv c = Speed of light (3.00 x 108 m/s) λ = Wavelength (shortest distance between equivalent points on a wave) ν= Frequency (# of waves that pass a given point per second) We also need to know………

11. We also need to know………

13. Ephoton= hv c = λv v= c / λ What can we determine from these equations? As energyof a photon increases, the frequency increases and the wavelength decreases

14. Example: A photon is emitted from an atom with an energy of 5.10 x 10-20J. What is the wavelength of the photon using correct significant figures? Ephoton= hv c = λv v = Ephoton / h v = 5.10 x 10-20 J / 6.626 x 10-34 J s v = 7.69695 x 1013 s-1 λ = c / v λ = 3.00 x 108 m/s / 7.69695 x 1013 s-1 λ = 3.89764 x 10-6 m = 3.90 x 10-6 m

15. 1. Ultraviolet radiation has a frequency of 6.8 × 1015s-1. Calculate the energy, in joules, of the photon. 2. Find the energy, in joules, of microwave radiation with a frequency of 7.91 × 1010s-1. 3. A sodium vapor lamp emits light photons with a wavelength of 5.89 × 10-7 m. What is the energy of these photons? 4. One of the electron transitions in a hydrogen atom produces infrared light with a wavelength of 7.464 × 10-6 m. What amount of energy causes this transition? 4.5 x 10-18 J 5.24 x 10-23 J 3.37 x 10-19 J 2.663 x 10-20 J Solve & use correct number of sig. figs. (Rally Coach)

16. Find the energy in kJ for an x-ray photon with a frequency of 2.4 × 1018 s-1. (1 kJ = 1000 J) 2. A ruby laser produces red light that has a wavelength of 500 nm. Calculate its energy in joules. (1m = 1 000 000 000 nm) 3. What is the frequency of UV light that has an energy of 2.39 × 10-18 J? 4. What is the wavelength and frequency of photons with an energy of 1.4 × 10-21 J? Solve & use correct number of sig. figs.

17. Ephoton= hv c = λv Equantum= Energy h = Planck’s constant (6.626 x 10-34 J s) v = Frequency *Note: Joule (J) is the unit of energy c = Speed of light (3.00 x 108 m/s) λ = Wavelength ν= Frequency