The _________ an electron falls the ________ energy released. day

1. Locate your Chapter # 3 Test. 2. Calculate and record your % grade. 3. Did you meet your goal? Why or why not. 4. Study (preparation) Plan for next test? 5. Record your new goal: - If you did not meet your goal it stays the same - If you did meet your goal – improve by one percentage points Day 2 1-2

1. Average your first three test grades. 2. Your new goal must be:  A passing grade  at least a two point improvement of your average unless your average is an A in which case you must improve by one point instead of two. Day 2 1-2

How do we know that light is made up of particles? day 2 1-2

Radiant Energy travels through space is energy that travels through space. light Is also known as light and electromagnetic radiation electromagnetic radiation. Major source is… THE SUN

Radiant Energy… Sun’s radiant energy is the result of nuclear fusion. Nuclear fusion – light nuclei combine to form heavier nuclei Fission vs. fusion?

The dual nature of light Particle??? Wave??? The dual nature – light can be viewed as a wave (continuous) OR a stream of extremely tiny, fast- moving particles (quantized)

The dual nature of light Particle??? Wave??? - Wave (continuous) as it travels through space - Particle (quantized) as it interacts with matter

Electromagnetic Spectrum ordered sequence light electromagnetic radiation The ordered sequence of all types of light or electromagnetic radiation.

The part of the electromagnetic spectrum that humans can see is called the … radio, micro, radar, IR, vis. Electromagnetic Spectrum vis., UV, X-ray, gamma, cosmic Low, low & Long! High, high & short!

Violet- High energy, bends more, inside of rainbow, 400 nm R O Y G B I V Red- Low energy, bends less, outside of rainbow, 700 nm

The energy of green light compared to that of red light is ___________.

Sir Isaac Newton …in the 1670’s, diffracted light with a prism and… Concluded that each color of light has a unique wavelength… energy

Light acts as a: wave as it … particle as it … Day 3 1-3

Electromagnetic Spectrum h a

amplitude (a) - affects brightness, half the height Frequency (ν) = number of crests passing a point in a period of time h = height, from crest to trough speed (c) = distance per unit time wavelength (λ) = crest to crest

λ = c/ν wavelength speed of light frequency

λ = c ÷ ν λ = wavelength c = speed of light = 3.00 * 10 8 m/s ν = fequency (s -1, Hz, 1/s) λ = (3.00*10 8 m/s)÷(93.1*10 6 s -1 ) λ = 3.22 m What is the wavelength if the frequency is 93.1*10 6 s -1

Quantum Theory Beginning of 20 th century – wave model is almost universally accepted. Problem = electromagnetic radiation emitted from hot objects

Can all light be described as continuous The energy of waves is continuous, or unbroken… When we look at an object as it is heated, what do we see? Quantum Theory … - quanta

Stop and summarize

Each color has its own energy And the energy changes with heating Quantum Theory … - quanta

Max Planck energy - related the frequency of light to its energy with the following: E = h Energyh=Planck’s const. E=Energy, h=Planck’s const. specific amounts His idea was that energy is absorbed and released in specific amounts. Quantum Theory Page e-34 J*s

specific amounts quantum quanta atoms His idea was that energy is absorbed and released in specific amounts. He called one piece, package, or bundle of energy one quantum. Bundles of energy were called quanta. He applied his quanta ideas to energy changes in atoms: Quantum Theory

atoms quantized continuous (wave-like) He applied his quanta ideas to energy changes in atoms: The energy of atoms is quantized. Formerly, scientists had thought that all energy was continuous (wave-like). Quantum Theory

Read / review section 5.3 AND complete #s on page 148 Assignment

1. Amplitude affects __________. 2. Shorter wavelengths = ______ frequencies 3. If a light wave has a wavelength (λ) of 3.0 * m, what is its frequency? higher brightness 1.0 * Hz Day

Day If a light wave has a wavelength of 1.0 * 10 8 m, what is its frequency? 2. High frequency = _____ energy and ______ wavelength λ = c ÷ ν 3.0 Hz High Short

Day λ = c/ν wavelength speed of light frequency

Day E = h Energyh=Planck’s const. E=Energy, h=Planck’s const e-34 J*s

Radiant Energy travels through space is energy that travels through space. light Is also known as light and electromagnetic radiation electromagnetic radiation. Major source is… THE SUN

The dual nature of light Particle??? Wave??? - Wave (continuous) as it travels through space - Particle (quantized) as it interacts with matter

amplitude (a) - affects brightness, half the height wavelength (λ) = crest to crest

1. Amplitude affects __________. 2. Longer wavelengths = ______ frequencies lower brightness Day High frequency = _____ energy and ______ wavelength 4. How can electrons move from one energy level to another? They must… High Short

Energy Source Absorbed Energy Energy Released

What does it mean if something is quantized? Day 3 1-3

Democritus’ atom Quantized Matter:Energy:Plank

Continuous: VS. Quantized: Height by step or rung Height on slide or ramp

Continuous: VS. Quantized: Ice cream scoops Soft-serve ice cream

Continuous: VS. Quantized: Digital thermometer Liquid thermometer

Quantum Theory Come up with your own: Continuous VS. Quantized: AND put it in your notes!

Light energy hits the electrons in metal- the light must be powerful enough. The electrons become excited, and they jump out of the metal. Electrons in the metal absorb the energy. Quantum Theory Quanta’s Ability:

The electrons fall down again, and create a spark or current. Examples: The luster of a shiny metal, Photoelectric cells (solar power) The electrons become excited, and they jump out of the metal. Quantum Theory

Albert Einstein - Imagined that light energy traveled in bundles - photons. 18 years later, Arthur Compton experimentally demonstrated that light is comprised of tiny particles, or photons, Quantum Theory

TODAY - Planck’s term quantum and Einstein’s term photon are used interchangeably. demonstrated that light is comprised of tiny particles, or photons, that can collide with electrons and cause them to move. Quantum Theory

TODAY - Planck’s term quantum and Einstein’s term photon are used interchangeably. Scientists also believe that light has properties of both waves and particles. Quantum Theory … - Dual nature of light

DEFINE: energy level AND atomic orbital AND Read section 5.1 AND answer questions 1, 2, 4, and 5 on page definitions and 4 questions Day 3 1-3