Radiant Energy travels through space is energy that travels through space. light Is also known as light and electromagnetic radiation electromagnetic radiation.

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

Sir Isaac Newton……in the 1670in the 1670’’s, 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

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

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

λ = c/νwavelength

speed of light

frequency

C = 3 * 108 m/s 1.0 * 1015

Hz

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

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=Planckh=Planck’’s s

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

Quantum Theory

6.626e-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

DemocritusDemocritus’’ 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

Quantized: VS. Continuous:

escalatorescalatorstairsstairs

Continuous: VS. Quantized:

Cheese singlesCheese singlesCheese blockCheese block

Quantum TheoryCome up with your own:

Continuous VS. Quantized:

AND put it in your notes!

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

The relationship between frequency , wavelength (), and color to the energy of light: ,

Color: red = low E, violet = high E

E : many photon punchesE: big gaps between consecutive photons.

Color: red = low E, violet = high E

each color has its own energy

color = type of light

The Effects of Different Photons:Microwaves: can’t feel

Infrared: feel with skin, warms or burns.

Visible light: see with eyes, heats when absorbed.

Ultraviolet: can’t feel or see, affects cells – freckles, tan, burn, cataracts.

X-rays: can’t feel or see, pass through body, but absorbed by bones and dense matter.Gamma rays: can’t see or feel, affects cells, causes mutations in cells and molecules.

The Effects of Different Photons:Ultraviolet: can’t feel or see, affects cells – freckles, tan, burn, cataracts.

Neils BohrTried to explain

why each element has its own unique (bright) line (bright) line spectrumspectrum. He studied HH.

Using previous discoveries- Bohr hypothesized that an atom’s electrons are located in specific energy levelsspecific energy levels. Each energy level, aka orbitorbit or shellshell is a set distance from the atom ’s nucleusnucleus. …

Bohr’s Hypothesis•In the line spectrum of an In the line spectrum of an atom, Bohr saw specific atom, Bohr saw specific colors.colors.

•Each specific color has a Each specific color has a specific energy.specific energy.

•That specific amount of That specific amount of energy is related to a energy is related to a specific specific distance from the distance from the nucleus.nucleus.

Energy Source

Absorbed EnergyEnergy Released

Ground vs. Excited States:An atom is in the groundground state when

its electrons fill the lowest possible energy levels that are closestclosest to the nucleus. This is when the atom is most stablestable.An electron can gaingain energy and jumpjump to a higher energy level. The electron must absorb an exact exact amountamount …

An electron can gaingain energy and jumpjump to a higher energy level. The electron must absorb an exact exact amountamount … of energy to make a jump to a specific energy level. The energy that the electron gains comes from a photonphoton.

Ground vs. Excited States:

When an atom’s electrons are in higher energy levels, the atom is in an excitedexcited state and is less stablestable. The atom prefers to be stable, so the electrons fallfall into lower energy levels that are not full. As the electrons fall, energy is releasedreleased in the form of visiblevisible or or invisible invisible lightlight.

atoms prefer…

• to be stable!

•to have low energy!

•to be in their ground state!

Energy within the atom?

Increases away from the nucleus

ENERGY

Quantum Mechanics

Mr. Bohr was concerned with calculating and predicting the line spectra of elements.

What happens when there is more than 1 electron?

Quantum Mechanics

Mr. Bohr was concerned with calculating and predicting the line spectra of elements. He wondered how electrons move and where they can be found in atoms. Bohr’s ideas worked well for hydrogen with 1 electron. …

What happens when there is more than 1 electron?

Quantum Mechanics

Bohr’s ideas worked well for hydrogen with 1 electron. … He predicted the infrared and ultraviolet bands of hydrogen’s emission spectrum. The equations he used came from Classical Mechanics, a branch of physics that describes the movements and interactions that are large enough to see.

But…Alas.. Bohr could not predict the bright-line spectra.

The laws of Classical Mechanics just don’t cut it for atoms and electrons.

Electrons are tricky… they and other subatomic particles like them have their own code of conduct… They behave differently than anything you may be able to see with your eyes or with any other object. New ideas needed to be looked into, and these new ideas became known as Quantum Mechanics.

Spectroscopes

Louis de BroglieOne of the first to

think that electrons possess wave wave propertiesproperties. He reasoned that since waves can act as particles do (taken from PlanckPlanck’’ss idea about lightlight), then particles might behave as waves do.

Large moving objects

Wavelengths are small and practically unnoticed.

For tiny subatomic particles…Wave properties areare importantimportant. As the size of the moving object decreases, its wavelength increasesincreases. The wavelength for a tiny electron can be as large as an entire atomatom.

So how does an electron move in an atom?

Bohr (and maybe you too…) thought that they moved in circularcircular or sphericalspherical orbits.

With de Broglie’s matter-matter-wave ideawave idea, now we theorize that electrons vibrate around the nucleus in a .

The Elusive Electron Evades Subatomic State Trooper!

Werner HeisenbergIn 1927, he

proposed the Uncertainty Uncertainty PrinciplePrincipleThis states that it is

impossible to know both the speedspeed and locationlocation of an electron at the same time.

Why is it so hard to pinpoint the electron?

To determine the speed and the location of an object, you must be able to SEE the object… light is bounced off the object when you see it.

Light is made up of quanta or photons.

When photons hit a speeding car, the car is unaffected. But when a photon hits a speeding electron, the electron will move or change direction. So, if a photon hits an electron and the light bounces off it into your eyes, you will see where the electron was, but you won’t know how fast it was going at the time.

Heisenberg

Explain the Heisenberg Uncertainty Principle.It is impossible to know both the speedspeed and locationlocation of an electron at the same time.

What, am I speeding?

The New Atom….If you cannot know the exact locationlocation and speedspeed of the electron, what is a scientist to do?With the use of calculus, the regionregion where the electron is most likely to be can be determined. These regions are called areas/zones of areas/zones of probabilityprobability

The most likely location of an electron is described by a wave of probability. This type of wave is actually a set patternpattern that forms a 3-D shape within the space of the atom. This wave pattern does not overlapoverlap itself and is known as a standingstanding wave.

http://www.youtube.com/watch?v=-gr7KmTOrx0

http://www.youtube.com/watch?v=3BN5-JSsu_4

http://www.youtube.com/watch?v=18BL7MKjtZM

Let’s now return to Bohr’s atomic model…

Bohr said that electrons are found in specific specific energy levelsenergy levels in an atom. Each energy level is a circle or sphere with a definite radius. …

Each energy level is a circle or sphere with a definite radius. … Bohr was close: What he thought as definite is actually the averageaverage radius. With quantum mechanics, the model of the energy level has expanded from a specific sphere to a region of probability that is like a cloudcloud around the nucleus.

Revisiting the Electron Cloud

Electron Position:

probability

orbitals

uncertainty

Electron Distribution Properties of element

How can the whereabouts of an electron compare to

an apartment building?

Floor/story of building

Suite/apartment

Bedroom

Female / Male

Energy level

Sublevel

Orbital for e-

couple

Spin

The Address of the The Address of the ElectronsElectrons

Just like people in an apartment, electrons have an address. The most probable location of an electron is described using quantum numbers. Each electron has 4 quantum numbers which each relays a different piece of information about the electron ’s possible whereabouts in the atom.

Pauli exclusion- no 2 electrons can have the same address!!! – same 4 quantum numbers

The Address of the The Address of the ElectronsElectrons

Energy levels - break into -

Describing Atomic Structure

Sublevels - break into -

Orbitals

Energy level – regions of space where there is a high probability of finding electrons

1

2

3

First sublevel – 2 electrons

Second sublevel – 6 electrons

Third sublevel – 10 electrons

Describing Atomic StructureSublevels

Describing Atomic Structure – Building an Address

Energy levels – designated by - #

Sublevels – designated by – letter (s, p, d, f) 1st Sublevel = s

2nd Sublevel = p 3rd Sublevel = d 4th Sublevel = f

1st Level = 1, 2nd Level = 2, etc. …

Describing Atomic Structure

# of energy level = # of sublevels in that energy level

Energy level 1 = 1 sublevel

Energy level 2 = 2 sublevels

Energy level 3 = 3 sublevels

…

Describing Atomic StructureSublevels

Energy still Increases away from the nucleus

E n

e r

g y

f

d

p

s

The New Atom?Do you think Bohr was

right or wrong?

Pauli exclusion?Energy levels - break into -

Sublevels - break into -

Orbitals

How do we define the

“address” of the

electron within the

atom?

1

2

3

Energy level 1, sublevel s, orbital 1s

Energy level 2, has two sublevels s and p, 2s orbital and 2p orbitals

Energy level 3, 3 sublevels s, p, and d, 3s orbital, 3p orbitals, and 3d orbitals

Electron Arrangement

Page 9

Electron ArrangementQuantum #s – specify the properties of atomic orbitals and the properties of electrons in those orbitals

Principle quantum # (n) – main energy level = 1, 2, 3…Angular momentum quantum # (l) – shape of the orbital = 0, 1, 2… (n-1)

0 = s, 1 = p, 2 = d, 3 = f

Magnetic quantum # (ml) – orientation of the orbital around the nucleus

Energy levels – designated by - # (n the principle quantum #)

Sublevels – designated by – letter (s, p, d, f) (l the angular momentum quantum #)

s = 0

p = 1

d = 2

f = 3

E n

e r g y

Energy still Increases away from the nucleus

Electron Arrangement

2 electrons fit in an orbital one spinning in the +1/2 orientation and one spinning in the -1/2 orientation

Electron Arrangement

How many electrons in an orbital?

How many orbitals in each sublevel?

Electron Arrangement

s = 1

p = 3

d = 5

f = 7

How many sublevels in each energy level?

Electron Arrangement

1 = _____ (__)

2 = _____ (____)

3 = _____ (______)

4 = _____ (__________) 1

2

3

xx

xx

xx

xx

4

3

2

1

Energy

Level

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx xxxx xx xx xx xx

s

p

d

f

Each x = an electron

Each xx = an orbital

Electron Arrangement

Taking a Look at Orbitals

S

P

D

Recall that atoms like to stay in their most stable (lowest energy) state = electron configuration

Electron Arrangement

electron configuration – notation used to show electron placement within sublevels

Skip ahead to page 11

Recall that atoms like to stay in their most stable (lowest energy) state.

1

2

3- Sublevels fill from the nucleus outward

Handouts

Electron Arrangement

Electron Arrangement

electron configuration – notation used to show electron placement within orbitals

electron Configuration for:

Si

C

1s22s22p63s23p2

1s22s22p2

Valence electrons?

Electron Configurations Practice:

S

F

1s22s22p63s23p4

Valence electrons?

1s22s22p5

Taking a Look at Orbitals

Taking a Look at Orbitals

Why does the ring

model work?

p – orbitals always occur in 3’s (one for each dimension)

3rd and 6th stopped

Taking a Look at Orbitals

3rd and 6th start

Why do exceptions exist?

How can you explain the

exceptions?

Electron Configurations using noble gas notation for:

K

Fe

[Ar]4s1

[Ar]4s23d6

Cd

Sn

[Kr]4d105s2

[Kr]4d105s25p2

1

2

3

Energy level 1, sublevel s, orbital 1s

Energy level 2, has two sublevels s and p, 2s orbital and 2p orbitals

Energy level 3, 3 sublevels s, p, and d, 3s orbital, 3p orbitals, and 3d orbitals

State

State

Is energy released or absorbed?Is energy released or absorbed?

xx

xx

xx

xx

4

3

2

1

Energy

Level

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx

xx xxxx xx xx xx xx

s

p

d

f

Each x = an electron

Each xx = an orbital

Electron Arrangement

In energy level 1 there is one s sublevel which contains one orbital and therefore 2 electrons. In energy level 2 there is an s sublevel and a p sublevel, the s sublevel contains one orbital (2 electrons) and the p sublevel contains 3 orbitals (6 electrons) for a total of 8 electrons. In energy level 3 …

electron Configuration for:

Si

C

1s22s22p63s23p2

1s22s22p2

Valence electrons?

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