Chapter 5 Light Energy and Electron Configurations

QUANTUM THEORY O Describes how electrons behave like both waves and particles O Is the modern theory of the atom O Properties of waves: property definition symbol SI units velocity distance traveled per secondcm/s Amplitude peak height above midline A m wavelengthpeak-to-peak distancem Frequency number of peaks passing by per seconds -1 (Hertz) λ ν

Relationship between frequency and wavelength

3 ways to tell a particle from a wave: O wave behaviorparticle behavior O waves interfereparticles collide O waves diffractparticles effuse O waves are delocalizedparticles are localized

The electromagnetic spectrum The speed of light is 3.00 x 10^8 m/s

Photoelectric Effect O An experiment designed to measure the energy carried by an electromagnetic wave O Shining light on alkali metals knocks electrons off O Brightness of light has NO EFFECT on the Kinetic Energy per electron O Brighter light simply ejects MORE electrons! O Red light can not eject electrons- Blue light can!

Planck’s Constant O The energy per electron can be calculated. O frequency-to-energy conversion factor is “h” (Planck's constant, 6.626× J/Hz) E = h * ν ENERGY = Planck’s Constant * frequency

Practice Problems: O A certain photon of light has a wavelength of 422 nm. What is the frequency of the light?

Practice Problems: O What is the energy of a quantum of light with a frequency of 7.39 x Hz?

Practice Problems: O A certain red light has a wavelength of 680 nm. What is the frequency of the light?

Practice Problems: O A certain blue light has a frequency of 6.91 x 1014 Hz. What is the wavelength of the light?