Warm Up  Write the correct answers for the following:  1) 2.00 x m = __________m  2) 1.23 x m = __________nm

Warm Up  Write the correct answers for the following:  1) 2.00 x m = __________m  2) 1.23 x m = __________nm  Answers: 200. m & 123 nm Think: 1) reduce by two places & increase 2.00 two places (the resulting number is still the same size!) 2) reduce by two places & increase 1.23 two places to preserve the size.

THE WAVE NATURE OF LIGHT Terms to Learn- Electromagnetic Radiation (EMR) A form of energy exhibiting wave-like behavior as it travels through space Neely’s Chemistry

THE WAVE NATURE OF LIGHT Electromagnetic Radiation (EMR) Examples: visible light; microwaves; radio waves; infrared radiation; ultraviolet radiation; X-Rays; gamma rays Neely’s Chemistry

THE WAVE NATURE OF LIGHT Terms to Learn- Wavelength (, greek letter “lambda”) The shortest distance between equivalent points on a continuous wave. (fig 5.2) Usually expressed in m, cm, m or nm Neely’s Chemistry

THE WAVE NATURE OF LIGHT Standing Wave (See Fig 5-2) Neely’s Chemistry

Amplitude  The wave’s height from origin to a crest, or from origin to a trough  The higher the amplitude, the brighter the light or emr.

Frequency (, the greek letter “nu”)  The number of waves passing a given point in one second.. (Fig 5.3)  The greater the frequency, the greater the energy.

Frequency Units: cps; 1/s or s -1 ; Hz = 1/s “Hertz”

Useful Conversions: CHANGE MULT. BY m to nm10 9 m to m10 6 Remember: G ||| M ||| k h da (m) d c m |||  ||| n

THE CONNECTION between frequency & wavelength  c = speed of light  c = 3.0 x 10 8 m/s c = 

THE CONNECTION between frequency & wavelength  c = 3.0 x 10 8 m/s 1. A red light is found to have a wavelength of 650 nm. What is the frequency of this radiation? (Note: nm = m) c = 

THE CONNECTION between frequency & wavelength  c = 3.0 x 10 8 m/s 2. A violet light has a frequency of 7.32 x Hz. What is the wavelength of this radiation? (Note: nm = m) c = 

THE CONNECTION between frequency & wavelength  c = 3.0 x 10 8 m/s 3. A green light has a wavelength of 4.90 x m. What is the speed of this electromagnetic wave? c = 

 Which wave has the higher freqency ()?  What happens to the frequency as the wavelength increases? What is this called (in math)?

THE EMR SPECTRUM Increasing ENERGY Radio microwave Infrared Visible UV X-Rays gamma rays SEE FIG 5-5 p 120 in Textbook Neely’s Chemistry

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