Chemistry Physics and the Quantum Mechanical Model

Section 3 Terms Amplitude Wavelength Frequency Hertz Electromagentic Radiation Spectrum Ground State Photons Heisenberg Uncertainty Principle

Star Light, Star Bright Light has dual personality, acting as a particle and a wave Characteristics of waves include: – AMPLITUDE – WAVELENGTH – FREQUENCY

AMPLITUDE: Distance from zero to waves highest or lowest point – Highest point is the crest, lowest point is the trough – Amplitude affects brightness, or the intensity of light

WAVELENGTH: The distance between crests or troughs – Represented by the Greek letter lambda ( λ ) – This affects the type of light Wavelength

FREQUENCY: The # of wave cycles to pass a given point per unit time – Represented by Greek letter nu ( ν ) – SI unit is cycles per second, or Hertz (Hz)

Waves with different frequencies look different A wave with a frequency of 4 Hz has two times more cycles per unit time than one with a frequency of 2 Hz

Practice Problems Draw six waves in two seconds with an amplitude of 3 Draw 3 waves in two seconds with an amplitude of 2 Draw a wave with a frequency of 4 Hz, an amplitude of 1 over two seconds

The relationship between wavelength, and frequency is: – c = λ ν, where c is always a constant, the speed of light Speed of light is 3.0 x 10 8 m/s (in a vacuum) – Wavelength and frequency are INVERSELY PROPORTIONAL to each other One goes up, the other goes down

Practice Problems Practice Problem – A radio wave has a wavelength of 700 m. If traveling in a vacuum, what is the waves frequency? – An x-ray with a wavelength of 4.5 x m is traveling through a vacuum. What is its frequency? – Red light has a wavelength of 480 nm. What is its frequency in a vacuum? – The frequency of a wave traveling through a vacuum is Hz (5 MHz). What is the wave’s wavelength?

ELECROMAGNETIC RADIATION: Energy waves that travel in a vacuum at 3.0 x 10 8 m/s – Includes radio, microwave, infrared, visible, ultraviolet, x-ray, and gamma rays – EM SPECTRUM: the range of different wavelengths of light – You must be able to reproduce this exact picture!!!

Atomic Spectra Electrons can absorb certain amounts of energy, such as the energy in electricity Electrons will then move into higher energy sublevels – Electrons now in an “excited” state Electrons will immediately release that energy and move back to their GROUND STATE – The lowest possible energy of the electron Released energy is in the form of a specific color of light When ordinary light is passed through a prism, it produces all visible colors

ATOMIC EMISSION SPECTRA: The unique color fingerprint of an element when its light is passed through a prism – Combination is unique to that element

Light behaves like a wave as well as a particle – PHOTON: A bundle of EM energy that interacts with matter similarly to a particle

Chapter 5 Review Pg – Problems 23, 26-29, 32-37, 41 – Question 73, calculate only the frequency of the waves; they give you the wavelengths in cm, you cannot use cm