wavelength, frequency, & energy of light byno chemistry 2013
TRANSCRIPT
Wavelength, Frequency, & Energy of Light
Byno Chemistry 2013
Why does Aluminum not burn? Why does Alcohol burn but it will not
react with anything else? Why does Aluminum react with
Hydrochloric Acid? Why does Calcium Carbonate react with
vinegar, but it doesn’t burn?
Discuss in your group
Identify and use the symbols for frequency and speed of light
Use 3x108 m/s as the value for the speed of light
Calculate E = hv using Planck’s constant Calculate c = λv using the speed of light
I can . . .
Symbol Meaning Value or Unit
c Speed of light 3x108 m/s
h Planck’s constant 6.63 x 10-34 Js
E Energy Joules (J)ν frequency Hertz (Hz)λ wavelength Nanometer (nm)
Symbols
Visible light breaks into a spectrum of colors depending on the wavelength of the light
Visible Light
Spectroscope
A spectroscope is a device used to separate the colors of visible light and measure their wavelengths
Electrons exist in the electron cloud but they can be found in distinct ‘levels’
They are the s-orbital, p-orbital, d-orbital, and f-orbital
Electrons can jump up from one orbital to the next when energy is applied to the atom
Electron Energy Levels
Ex. Cadmium
Groups 1 and 2, and Helium
S-Orbital
Groups 13-18 (except Helium)
P-orbital
Transition metals – Groups 3-12
D-orbital
Lanthinide and Actinide series – Rare Earth Metals
F-orbital
Electrons
The motion of electrons in the electron cloud of an atom creates low energy waves such as visible light and radio waves
The energy is the result of electrons hopping from one level up to the next
Energy is emitted when the electron falls back to the original level
An element can react with another element if it has electrons that can move
When a chemical substance reacts with another, the electrons move and give off energy in the form of light
Reactivity
The energy of the electron’s movement in a chemical reaction can be calculated
Wavelength
Speed of light (m/s)
Wavelength
(m)
Frequency (Hz)
Example: A helium laser emits light with a wavelength of 633 nm. What is the frequency of the light?
Now that we know the wavelength, we can calculate the energy of the electron
Energy
Energy
(J)
Frequency
(Hz)
h (Planck’s Constant)6.63 x 10-34
Js
Example: A helium laser emits light with a wavelength of 633 nm. What is the energy of its electrons? We previously
calculated frequency = 6.00 Hz
What is the energy of light whose wavelength is 4.06 x 10-11 m?
Practice
c÷λ = νν = 3.8x108 m/s ÷ 4.06x10-11 mν = 7.39x1018 Hz
E = h × νE = 6.63x10-34 Js × 7.39x1018 HzE = 4.9x10-15 J