QUANTIZATION OF THE ATOM

DATE TITLE PAGE #

TABLE OF CONTENTS

X Chemical/Physical IP 28

X Chemical/Physical 29

X Atoms & Elements 30

X Book Learning (Theory) 31 – 32

X History of the Atomic Theory notes 33

X History IP 34

X Structure of the Atom notes 35

X Structure of the Atom IP#1 & 2 36

X Bohrs Model 37

X Bohr IP#1 38

X Bohr IP#2 (PT) 39

THE CURRENT ATOM

Electrons “-”

Protons “+”

Neutrons “0”

+

+

+

0

0

0

0

BOHR’S MODEL

• Bohr studied the light produced

when atoms were excited by

heat or electricity.

• Rutherford's model

couldn't explain why

unique colors were

obtained by atoms of

different elements.

BOHR’S MODEL

• Electrons orbit the nucleus like planets orbit the sun.

• Bohr proposed that electrons are in orbits & when excited jump to a higher orbit. When they fall back to the original they give off light.

Lower energy level

Higher energy

level

BOHR’S MODEL

• Each electron shell (ring) can hold a

certain number of electrons

• Electron shells are filled from the

inside out

+ Noble Gases have full outer electron

shells and are STABLE, NON-

REACTIVE

Argon (Ar)

“Noble Gas”

BOHR’S MODEL• The electrons in the

outermost ring (valence

shell) are called valence

electrons

+ The number of electron

shells is the same as the

period number

+ The number of valence

electrons is the same as

the group number

Valence

e-

Valence

shell

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USE THE PERIODIC TABLE TO CREATE YOUR BOHR MODEL!

• Protons, neutrons, electrons

• Rings (energy shells)

• How you should “fill up” each ring

• Valence electrons

CFU #1: CARBON

• Total electrons

• How many on ring 1?

• How many on ring 2 (valence)?

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CFU #1: NEON• Total electrons

• How many on ring 1?

• How many on ring 2 (valence)?

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Non- METALS

METALS

1 2 GROUPS “valence electrons” 3 4 5 6 7 8

1. Sulfur (S)2. Fluorine (F)

3. Aluminum (Al)

HOW MANY VALENCE ELECTRONS?

CFU #3

Non- METALS

METALS

1. Sulfur (S)2. Fluorine (F)

3. Aluminum (Al)

1

2

3

4

5

SHELLS

HOW MANY SHELLS (RINGS)?

KEY

CFU #2

CFU!

Non- METALS

METALS

1 2 GROUPS “valence electrons” 3 4 5 6 7 8

1

2

3

4

5

SHELLS

CFU!

Which element has 18 valence electrons, 4 shells?CFU!

Which element has 2 valence electrons, 5 shells?CFU! e

Which element has 5 valence electrons, 3 shells?

BONUS

DRAWING BOHR MODELS

1. Draw the nucleus.

2. Write the number of neutrons and the number of protons in the nucleus.

3. Draw the first energy level.

4. Draw the electrons in the energy levels according to the rules below. Make sure you draw the electrons in pairs.

5. Keep track of how many electrons are put in each level and the number of electrons left to use.

You must fill one level before going

on to draw the next level!

GUIDED PRACTICE

• Protons: _____ Neutrons: _____Electrons: ______

• How many energy shells will this have? ____

• How many valence (outer) electrons does this element

have? ____

• Bohr Model:

11

Na

Sodium

22.990

11 12 113

1

GUIDED PRACTICE

• Protons: _____ Neutrons: _____Electrons: ______

• How many energy shells will this have? ____

• How many valence (outer) electrons does this element

have? ____

• Bohr Model:

15

PPhosphorous

30.974

15 16 153

5

GUIDED PRACTICE

• Protons: _____ Neutrons: _____Electrons: ______

• How many energy shells will this have? ____

• How many valence (outer) electrons does this element

have? ____

• Bohr Model:

6

C

Carbon

12.011

6 6 62

4

WE DO – BOHR MODEL RACES

• You will see a symbol displayed.

• Create an accurate Bohr Model using what you

know about atoms and energy level rules.

• Check answers when time is up.

Any beads found on the floor will

result in class materials deductions

KEY

helium

lithium

beryllium

boron

carbon

nitrogen

oxygen

fluorine

neonFull valence shell = non-reactive

ABSORPTION AND EMISSIONHOW IS LIGHT ABSORBED AND

EMITTED BY ATOMS IN INTERSTELLAR GASES OR STARS?

THE ELECTROMAGNETIC SPECTRUM

low frequency

low energy

High frequency

High energy

MODELS OF LIGHT

LIGHT IS A WAVE LIGHT IS A PARTICLE

So which one is

right?

They are both right...and they are both wrong.

That’s called W A V E - P A R T I C L E duality

•In some experiments, the wave model works

best.

•In other experiments, the particle model

works best.

•Thus, we use both.

LIGHT IS A WAVESynonyms for “light”

• Electromagnetic wave

• Electromagnetic radiation

• Radiation

Visible light is light that oureyes are sensitive to;however, that is not theonly type of electromagneticradiation

WAVELENGTH VS. FREQUENCY

Wavelength ()the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.

Frequency (f)the rate at which a vibration

occurs that constitutes a

wave, either in a material (as

in sound waves), or in an

electromagnetic field (as in

radio waves and light),

usually measured per second.

CALCULATIONS BETWEEN WAVELENGTH, FREQUENCY AND

ENERGY Wavelength (): the distance between

successive crests of a wave, especially

points in a sound wave or

electromagnetic wave.

Speed of Light (c): the distance light

can travel in a unit of time through a

given substance.

In a vacuum, v = c = 3.00 x 108 m/s.

Frequency (f): the rate at which a

vibration occurs that constitutes a

wave, either in a material (as in

sound waves), or in an

electromagnetic field (as in radio

waves and light), usually measured

per second.

Check for Understanding

Find Frequency (v) using the equation A gamma ray has a wavelength of 0.039 nm. What is the frequency of the wave?

Find Wavelength () using the equation What is the wavelength of an X ray that has a frequency of 7.8 X 1017 Hz?

∁= 𝜆 ∗ 𝑣

Speed of light = 3.00 x 108 m/s

𝑐

𝜆

𝑐

𝑣

LIGHT COMES IN MANY WAVELENGTHS

• White light is a combination of all colors in the color spectrum.

• When white light passes through a glass prism (or a diffraction grating), it separates

into colors.

• These colors have different wavelengths.

• This group of wavelengths is the visible part of the electromagnetic spectrum.

• When you “see” the entire spectrum with no thin dark bands, it is a continuous

spectrum.

ELECTROMAGNETIC SPECTRUM

Add colors to this portion:

NOTE:

• Energy

• Frequency

• wavelength

CHECK FOR UNDERSTANDING

1. What is the wavelength range for the visible light spectrum?

2. Which color of light has a longer wavelength purple or red?

3. Suppose that a certain medical treatment requires exposing certain tissues to high frequency radiation. Would that radiation likely be gamma rays or radio waves?

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LIGHT AS A PARTICLE(SMALL REGION OF SPACE)

• A photon is a “particle” or

“packet” of energy according to

Max Planck called a QUANTUM

• A quantum of energy is the

minimum amount of energy that

can be lost or gained by an atom.

• High frequency photons have high

energy

• Low frequency photons have low

energy

BOHR MODEL

• The Bohr model is a planetary model, where the electron orbits the nucleus like a planet orbits the Sun.

• An electron is only allowed in DISCRETE orbits (n=1, n=2, n=3, etc.)

• The higher the orbit, the higher the energy of the electron.

ABSORPTION, EMISSION, AND ENERGY

• When an atom absorbs a photon, it gains

energy.

• When an atom loses energy, it emits a photon.

• An atom can only absorb or emit photons of

“specific” energy.

• Those “right energies” correspond to the

DIFFERENCES in energy between the allowed

energy levels.

Absorption

photon

Emission

photon

HYDROGEN ENERGY SPECTRUM

-13.6 eV

-3.40 eV

-1.51 eV

-0.850 eV

-0.544 eVn=5

n=4

n=3

n=2

n=1

Energy Level Energy

• Only certain energies are allowed

• The change in the energy between two levels

corresponds to a certain color photon absorbed or

emitted by the atom.

• The lowest energy level is the ground state.

• Higher energy levels are called excited states.

ground

excited

Lower energy level

“ground state”

Higher energy

level

“excited state”

!

CFU

1. If an atom is in the ground state (n=1)

and is excited to n=3, what energy

photon was absorbed?

2. If a hydrogen atom is in the state n=4,

to what level must it “fall” in order to

emit a blue photon?

ABSORPTION SPECTRUM

• If light of a continuous spectrum is incident on a gas of hydrogen atoms, then electrons will absorb some of the light.

• As a result, bands of the spectrum are missing; these are called absorption lines.

EMISSION SPECTRUM

• If excited hydrogen atoms fall to lower energy states, photons will be emitted.

• The emitted photons will be detected as light of certain bands of frequencies (i.e. colors).

• The collection of bands (or lines) forms an emission spectrum.