The _________ an electron falls the ________ energy released.

day 3 12-15

day 3 12-15

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 Energyis energy that travels travels through spacethrough space.

Is also known as lightlight and

electromagnetic electromagnetic radiationradiation.

Major source is…THE SUNTHE SUN

Radiant Energy…Sun’s radiant energy

is the result of nuclear fusion.Nuclear fusion – light nuclei combine to form heavier nucleiFission vs. Fission vs. fusion?fusion?

The dual nature of lightParticle??? 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 lightParticle??? Wave???

- Wave (continuous) as it travels through space

- Particle (quantized) as it interacts with matter

Electromagnetic Spectrum

The ordered sequenceordered sequence of all types of lightlight or electromagnetic electromagnetic radiationradiation.

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-Violet-

High High energy, energy, bends more, bends more, inside of inside of rainbow, rainbow, 400 nm400 nm

R O Y G B I V

Red-Red-

Low Low energy, energy, bends less, bends less, outside of outside of rainbow, rainbow, 700 nm700 nm

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

Sir Isaac Newton……in the 1670’s, in the 1670’s, diffracted light diffracted light with a with a prismprism and…and…

Concluded that Concluded that each color of light each color of light has a unique has a unique wavelength… wavelength… energyenergy

Light acts as a:

wave as it …

particle as it …

Day 3 1-3

Electromagnetic Spectrum

h

a

amplitude (a) - affects amplitude (a) - affects brightness, brightness, half the half the height height

Frequency (Frequency (νν) = number of ) = number of crests passing a crests passing a point in a point in a period of time period of time

h = height, from crest to h = height, from crest to troughtrough

speed (c) = distance per speed (c) = distance per unit timeunit time

wavelength (wavelength (λλ) = crest to ) = crest to crestcrest

λ = c/νwavelength

speed of light

frequency

λ = c ÷ νλ = wavelengthc = speed of light = 3.00 * 108 m/sν = fequency (s-1, Hz, 1/s)

λ = (3.00*108 m/s)÷(93.1*106 s-1)λ = 3.22 m

What is the wavelength if the frequency is 93.1*106 s-1

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

Can all light be described asThe energy of waves is continuouscontinuous, 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 Each color has its own energy energy AndAnd the the energy changes with energy changes with heatingheating

Quantum Theory

… - quanta

Max Planck- related the frequency of light to its energy energy with the following: E = h E=EnergyEnergy, h=Planck’s h=Planck’s

const.const.His idea was that energy is absorbed and released in specific amountsspecific amounts.

Quantum Theory

Page 1436.626e-34 J*s

His idea was that energy is absorbed and released in specific amountsspecific amounts. He called one piece, package, or bundle of energy one quantumquantum. Bundles of energy were called quantaquanta. He applied his quanta ideas to energy changes in atomsatoms:

Quantum Theory

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

Quantum Theory

Read / review section 5.3 AND complete #s 19-24 on page 148

Assignment

1. Amplitude affects __________.

2. Shorter wavelengths = ______ frequencies

3. If a light wave has a wavelength (λ) of 3.0 * 10-7 m, what is its frequency?

higher

brightness

1.0 * 1015 Hz

Day 1 12-21

Day 3 1-3

1. If a light wave has a wavelength of 1.0 * 108 m, what is its frequency?

2. High frequency = _____ energy and ______ wavelength

λ = c ÷ ν

3.0 HzHigh

Short

Day 3 1-3

λ = c/νwavelength

speed of light

frequency

Day 3 1-3

E = h E=EnergyEnergy, h=Planck’s h=Planck’s const.const.

6.626e-34 J*s

Radiant Energyis energy that travels travels through spacethrough space.

Is also known as lightlight and

electromagnetic electromagnetic radiationradiation.

Major source is…THE SUNTHE SUN

The dual nature of lightParticle??? Wave???

- Wave (continuous) as it travels through space

- Particle (quantized) as it interacts with matter

amplitude (a) - affects amplitude (a) - affects brightness, brightness, half the half the height height

wavelength (wavelength (λλ) = crest to ) = crest to crestcrest

1. Amplitude affects __________.

2. Longer wavelengths = ______ frequencies

lower

brightness Day 3 1-3

3. High frequency = _____ energy and ______ wavelength

4. How can electrons move from one energy level to another? They must…

HighShort

Energy Source

Absorbed EnergyEnergy Released

What does it mean if something is quantized?

Day 3 1-3

Democritus’ Democritus’ atomatom

Quantized QuantizedMatter: Energy:PlankPlank

Continuous: VS. Quantized:

Height by step or Height by step or rungrung

Height on slide or rampHeight on slide or ramp

Continuous: VS. Quantized:

Ice cream scoopsIce cream scoopsSoft-serve ice creamSoft-serve ice cream

Continuous: VS. Quantized:

Digital Digital thermometerthermometer

Liquid Liquid thermometerthermometer

Quantum TheoryCome 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 TheoryQuanta’s Ability:

The electrons fall down again, and create a spark or current.Examples: The luster of a Examples: The luster of a shiny metal, Photoelectric shiny metal, Photoelectric cells (solar power)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 132

2 definitions and 4 questions

Day 3 1-3