Wavelength, Frequency, & Energy of Light Byno Chemistry 2013

Discuss in your group 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?

I can . . . 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

Symbols Symbol Meaning Value or Unit c Speed of light 3x108 m/s h Planck’s constant 6.63 x 10-34 Js E Energy Joules (J) ν frequency Hertz (Hz) λ wavelength Nanometer (nm)

Visible Light Visible light breaks into a spectrum of colors depending on the wavelength of the light

Spectroscope A spectroscope is a device used to separate the colors of visible light and measure their wavelengths

Electron Energy Levels 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

Ex. Cadmium

S-Orbital Groups 1 and 2, and Helium

P-orbital Groups 13-18 (except Helium)

D-orbital Transition metals – Groups 3-12

F-orbital Lanthinide and Actinide series – Rare Earth Metals

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

Reactivity 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

Wavelength The energy of the electron’s movement in a chemical reaction can be calculated 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?

Energy Now that we know the wavelength, we can calculate the energy of the electron Energy (J) Frequency (Hz) h (Planck’s Constant) 6.63 x 10-34 Js 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

Practice What is the energy of light whose wavelength is 4.06 x 10-11 m? c÷λ = ν ν = 3.8x108 m/s ÷ 4.06x10-11 m ν = 7.39x1018 Hz E = h × ν E = 6.63x10-34 Js × 7.39x1018 Hz E = 4.9x10-15 J