Chemistry 5.3

“Physics and the Quantum Mechanical Model”

Read pg. 138 p. 1

I. Light and Atomic Spectra

A. Question???

“Is light a particle or a wave?”

-Newton = particle

-Most Scientists = wave

B. Electromagnetic Radiation

1. Includes radio waves, microwaves, infrared, visible light, U.V., X-rays, and gamma.

2. Travel = 3.0 x 108 m/s (c)What is this in mph? 680,000,000 mph

C. Wave Parts

Wavelength (λ)

Crest

Trough

Amplitude

Origin

Frequency (ν) = the number of waves cycles that pass over a given period of time

Hertz (Hz) = wave cycles per second Formula C = λ ν

gamma X-rays U.V. visible infrared radio

When white light shines through a prism or through water vapor like this rainbow, the white light is broken apart into the colors of the visible light spectrum.

Which color of the rainbow has the shortest wavelength? violet

Which color of the rainbow has the highest frequency? violet

D. Elements + energy

1. Elements emit light when they are excited by energy.

2. Used to determine the unknown substances by the color it gives off.

-stars, inaccessible substances, bodies of gases, etc.

In – Class Assignment

1. Calculate the wavelength in cm of the yellow light emitted by a sodium lamp if the frequency of the radiation is 5.10 x 1014 Hz (s-1)?

2. What is the wavelength of radiation in cm with a frequency of 1.50 x 1013 s-1? Does this radiation have a shorter or longer wavelength than red light?

3. What frequency is radiation in cm with a wavelength of 5.00 x 10-6 cm? In what region of the electromagnetic spectrum is this radiation?

5.88 x 10-5 cm

2.00 x 10-3 cm

6.00 x 1015 cm

Orange - Yellow

Longer wavelength

II. Atomic Spectra

A. Ground State

1. An electron in its lowest level. (N1)

2. Energy to the electron

a. Specific amounts

3. Electron jumps to…N 2,3,4,5,6…

a. Based on specific amount

4. Energy is lost and a photon is released (light) as it travels back down to its regular level.

Energy Level 1

EnergyLevel 2

e-

Photon of light

Fig 5.14

B. Series1. Lyman Series

-ground state level 1-produces U.V. Rays

2. Balmer Seriews-ground state level 2-produces Visible Rays

3. Paschen Series-ground state level 3-produces Infrared Rays