1. What is an atomic emission spectra?

2. Why is Bohr’s model of the atom considered quantized?

Question of the Day

Day 1 1-6

The spectra (energy) given off when an atom’s electrons are excited.

Electrons are found in specific energy levels.

1. Amplitude affects __________.

2. Longer wavelengths = ______ frequencies

lower

brightness

3. High frequency = _____ energy and ______ wavelength

HighShort

Who demonstrated photons can move electrons?

How?

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

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 energyspecific energy levelslevels. Each energy level, aka orbitorbit or shellshell is a set distance from the atom ’s nucleusnucleus. …

… Electrons jumpjump or fallfall from one energy level to another, while simultaneously gaining or losing energyenergy. Electrons are not permitted to stop betweenbetween energy levels.

Neils Bohr… 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 colorscolors..

•Each specific Each specific colorcolor has a has a specific specific energyenergy..

•That specific amount of That specific amount of energyenergy is related to a is related to a specific specific distancedistance from the from the nucleus.nucleus.

DEFINE:

energy level AND atomic orbital

AND Read section 5.1 AND answer

questions 1, 2, 4, and 5 on page 132

BINDER CHECKS!!!

What does it mean if something is quantized?

Day 2 1-9

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!

Drawing:

Day 2 1-9

Energy Source

Absorbed EnergyEnergy Released

Energy within the atom?

Increases away from the nucleus

ENERGY

Radiant AcrosticRADIANT

1. In order to become excited an electron must _____________.

2. The most stable state for an atom is the ______ state.

3. Radiant energy = __________________

Question of the Day

Day 3 1-10

4. Energy within an atom increases …

absorb energy

ground

sun / electromagnetic radiation

h

a

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.

Friday 1-10 day 3

1. If an electron absorbs energy it moves into an _______ state.

2. Almost immediately it falls back down to the _______ state.

Question of the Day

Day 4 1-13

excited

ground

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.

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.

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.

Quick Draw

radiant energy

Excited state

wavelength

electron cloud model

Bohr

Radiant AcrosticRADIANT

Radiant AcrosticRADIANT