Chapter 5 Electrons in Atoms Light and quantized energy.

Chapter 5Chapter 5Electrons in AtomsElectrons in Atoms

Light and quantized energyLight and quantized energy

Chapter 5Chapter 5Arrangement of ElectronsArrangement of Electrons

I.I. Electromagnetic WavesElectromagnetic WavesII.II. Dual Nature of LightDual Nature of LightIII.III. Bohr Model of the AtomBohr Model of the AtomIV.IV. Quantum Model Quantum Model V.V. Quantum NumbersQuantum NumbersVI. Determining Number of Orbital VI. Determining Number of Orbital

Types and ElectronsTypes and ElectronsVII. Electron ConfigurationsVII. Electron Configurations

II. . Electromagnetic WavesElectromagnetic Waves

A.A. Definition of a Definition of a WaveWave

1. method by which energy is transferred 1. method by which energy is transferred

from one point to anotherfrom one point to another

B.B. Definition of Definition of Electromagnetic WaveElectromagnetic Wave

1. a form of energy that exhibits wave-1. a form of energy that exhibits wave-

like behavior as it travels through like behavior as it travels through

spacespace

I. Wave Particles Nature of I. Wave Particles Nature of LightLight

A.A. Electromagnetic radiation- form of energy Electromagnetic radiation- form of energy that exhibits wavelike particles.that exhibits wavelike particles.

Includes many kinds of waves Includes many kinds of waves

All move at 3.00 x 10All move at 3.00 x 1088 m/s ( c) speed of light m/s ( c) speed of light

1. Light is a kind of electromagnetic radiation.1. Light is a kind of electromagnetic radiation.a. The study of light led to the a. The study of light led to the

development of the quantum mechanical development of the quantum mechanical model.model.

B. Parts of WaveB. Parts of Wave

1.Origin - the base line of the energy1.Origin - the base line of the energy2.Crest - high point on a wave2.Crest - high point on a wave3. Trough - Low point on a wave3. Trough - Low point on a wave4. Amplitude - distance from origin to crest4. Amplitude - distance from origin to crest5. Wavelength - distance from crest to crest5. Wavelength - distance from crest to crest6. Wavelength - is abbreviated 6. Wavelength - is abbreviated Greek Greek

letter lambda.letter lambda.

Parts of a waveParts of a wave

Wavelength

AmplitudeOrigin

Crest

Trough

C.Properties of Electromagnetic WavesC.Properties of Electromagnetic Waves

1. can travel in a vacuum1. can travel in a vacuum

2. travel at 3 x 102. travel at 3 x 101010 cm per second cm per second

(this is the speed of light)(this is the speed of light)

3. vary in wavelength and frequency3. vary in wavelength and frequency

a. a. wavelengthwavelength – distance between – distance between

corresponding points on wavescorresponding points on waves

b.b. frequencyfrequency – the number of waves – the number of waves

that pass a point in a given amountthat pass a point in a given amount

of time (usually one second) of time (usually one second)

Electromagnetic WaveElectromagnetic Wave

Disturbance in a magnetic field is perpendicular to a Disturbance in a magnetic field is perpendicular to a disturbance in an electric fielddisturbance in an electric field

C. FrequencyC. Frequency

1. The number of waves that pass a given 1. The number of waves that pass a given point per second.point per second.

2. SI units are hertz (hz) or cycles/sec 2. SI units are hertz (hz) or cycles/sec

3. Abbreviated 3. Abbreviated the Greek letter nuthe Greek letter nu

c = c =

C. FrequencyC. Frequency andand wavelengthwavelengthwatch slinkywatch slinky

1. Are inversely related1. Are inversely related

2. As one goes up the other goes down.2. As one goes up the other goes down.

3. Different frequencies of light are different 3. Different frequencies of light are different colors of light.colors of light.

4. There is a wide variety of frequencies4. There is a wide variety of frequencies

5. The whole range is called a spectrum5. The whole range is called a spectrum

Radiowaves

Microwaves

Infrared .

Ultra-violet

X-Rays

GammaRays

Low energy

High energy

Low Frequency

High Frequency

Long Wavelength

Short WavelengthVisible Light

EMSEMS

D.D. Examples of Electromagnetic WavesExamples of Electromagnetic Waves

1. radio waves1. radio waves

2. microwaves2. microwaves

3. infrared3. infrared

4. white light (visible spectrum)4. white light (visible spectrum)

5. ultraviolet light5. ultraviolet light

6. X-rays6. X-rays

7. gamma radiation 7. gamma radiation

Continuous Electromagnetic SpectrumContinuous Electromagnetic Spectrum---------> increasing wavelength ----------->---------> increasing wavelength ----------->

E. Wavelength, Frequency and EnergyE. Wavelength, Frequency and Energy 1. wavelength and frequency 1. wavelength and frequency a. the frequency increases as the a. the frequency increases as the wavelength decreases wavelength decreases b. inverse relationshipb. inverse relationship 2. frequency and energy2. frequency and energy a. as the frequency increases thea. as the frequency increases the energy increases energy increases b. direct relationshipb. direct relationship

Electromagnetic SpectrumElectromagnetic Spectrum----------------> increasing frequency ---------------->----------------> increasing frequency ---------------->---------------> decreasing wavelength ----------------> ---------------> decreasing wavelength ---------------->

Diagram Showing Wavelength andDiagram Showing Wavelength and Frequency Frequency

F.F. Types of SpectraTypes of Spectra

1. 1. continuous continuous – all wavelength within a – all wavelength within a

given range are includedgiven range are included

2. 2. electromagneticelectromagnetic – all electromagnetic – all electromagnetic

radiation arranged according to radiation arranged according to

increasing wavelengthincreasing wavelength

a. unit for wavelength ranges froma. unit for wavelength ranges from

meters to nanometersmeters to nanometers

b. unit for frequency is b. unit for frequency is hertzhertz (Hz) (Hz)

3. 3. Visible spectrumVisible spectrum - light you can see - light you can see (ROY-G-BIV) (ROY-G-BIV) a. red has the longest wavelength anda. red has the longest wavelength and the smallest frequencythe smallest frequency b. violet has the shortest wavelength b. violet has the shortest wavelength and the greatest frequencyand the greatest frequency4. 4. Bright Line spectrum (emission spectrum)Bright Line spectrum (emission spectrum) a. bands of colored light emitted by a. bands of colored light emitted by excited electrons when they return to excited electrons when they return to the ground state the ground state

G. SpectroscopyG. Spectroscopy

1. 1. emission spectraemission spectra of a substance is of a substance is

studied to determine its identity studied to determine its identity

2. 2. spectroscopespectroscope – instrument that – instrument that

separates white light into a spectrumseparates white light into a spectrum

3. 3. spectral linesspectral lines – represent wavelength – represent wavelength

of light emitted when excited electrons of light emitted when excited electrons

fall back to the ground statefall back to the ground state

Emission Spectrum (Line Spectrum) Emission Spectrum (Line Spectrum)

Picture of a SpectroscopePicture of a Spectroscope

Emission SpectrumEmission Spectrum

Spectral line activitySpectral line activity

Put on spectrum glassesPut on spectrum glasses

View Hydrogen argon, helium,etc.View Hydrogen argon, helium,etc.

II. Light Has a Dual Nature!!!II. Light Has a Dual Nature!!!A.A. Light can act like a particle or a waveLight can act like a particle or a wave 1. emission and absorption of light by 1. emission and absorption of light by matter can not be explained by wavematter can not be explained by wave theorytheory 2. only certain frequencies of light 2. only certain frequencies of light produce the produce the photoelectric effectphotoelectric effect a. emission of electrons by some a. emission of electrons by some metals when they are exposed to metals when they are exposed to lightlight

II. LightII. Light is a Particleis a Particle Energy is quantized.Energy is quantized. Light is energyLight is energy Light must be quantizedLight must be quantized These smallest pieces of light are called These smallest pieces of light are called

photons.photons. Energy and frequency are directly related. Energy and frequency are directly related.

LightLight isis a particlea particle

Missing the video Missing the video

Light Has a Dual Nature (Particle + Wave)Light Has a Dual Nature (Particle + Wave)

Light Interference Pattern (Wave Nature)Light Interference Pattern (Wave Nature)

3. In 1900 3. In 1900 Max PlanckMax Planck observed that a hot observed that a hot object loses energy in packets called object loses energy in packets called quanta quanta

a. this energy is directly related to thea. this energy is directly related to the

wave frequency ( E = hv)wave frequency ( E = hv)

b. in 1905 b. in 1905 EinsteinEinstein said this relationship said this relationship

held for all electromagnetic radiationheld for all electromagnetic radiation

Photoelectric Effect – Particle NaturePhotoelectric Effect – Particle Nature

Light hits a metal and electrons are released and an Light hits a metal and electrons are released and an electric current may be produced electric current may be produced

II. Light is a particle II. Light is a particle

A.A. photoelectric effect – photoelectric effect – emission of electrons emission of electrons by metals when light by metals when light shines on themshines on them

( must be a specific ( must be a specific frequency)frequency)

Which has more energy a Which has more energy a marble or a bowling ball?marble or a bowling ball?

A marble can’t knock down a A marble can’t knock down a block no matter how block no matter how many times you throw it.many times you throw it.

Cached.url

Photoelectric Effect – Particle Nature of LightPhotoelectric Effect – Particle Nature of Light

Only light of a certain frequency or higherOnly light of a certain frequency or higher will cause the photoelectric effectwill cause the photoelectric effect

4. Vocabulary4. Vocabulary

a. a. quantum quantum – quantity of energy gained – quantity of energy gained

or lost by an atom when electrons are or lost by an atom when electrons are

excitedexcited

b. b. photonphoton – a quantum of light – a quantum of light

c. c. ground stateground state – lowest energy level of – lowest energy level of

an atoman atom

d. d. excited stateexcited state – a heightened state of – a heightened state of

energy in an atom energy in an atom

Energy and frequencyEnergy and frequency E = h x E = h x E is the energy of the photonE is the energy of the photon is the frequencyis the frequency h is Planck’s constant h is Planck’s constant h = 6.6262 x 10 h = 6.6262 x 10 -34 -34 Joules sec.Joules sec. joule is the metric unit of Energyjoule is the metric unit of Energy

The Math in Chapter 5The Math in Chapter 5 Only 2 equationsOnly 2 equations c = c = E = hE = h Plug and chug.Plug and chug.

ExamplesExamples What is the wavelength of blue light with What is the wavelength of blue light with

a frequency of 8.3 x 10a frequency of 8.3 x 101515 hz? hz? What is the frequency of red light with a What is the frequency of red light with a

wavelength of 4.2 x 10wavelength of 4.2 x 10-5 -5 m?m? What is the energy of a photon of each of What is the energy of a photon of each of

the above?the above?

Atomic SpectrumAtomic Spectrum

How color tells us about atomsHow color tells us about atoms

The Flame TestThe Flame Test

A basic form of Emission A basic form of Emission SpectroscopySpectroscopy

PrismPrism White light is made White light is made

up of all the colors of up of all the colors of the visible spectrum.the visible spectrum.

Passing it through a Passing it through a prism separates it.prism separates it.

If the light is not whiteIf the light is not white By heating a gas with By heating a gas with

electricity we can get electricity we can get it to give off colors.it to give off colors.

Passing this light Passing this light through a prism does through a prism does something different.something different.

Atomic SpectrumAtomic Spectrum Each element gives Each element gives

off its own off its own characteristic colors.characteristic colors.

Can be used to Can be used to identify the atom.identify the atom.

How we know what How we know what stars are made of.stars are made of.

• These are called discontinuous spectra

• Or line spectra

• unique to each element.

• These are emission spectra

• The light is emitted given off.

You and Your PartnerYou and Your Partner

Label each splint, by metal, take two splints Label each splint, by metal, take two splints for each metal for each metal

Dip the wet splint in the salt solutions Dip the wet splint in the salt solutions Insert wooden splint at tip of inner cone…Insert wooden splint at tip of inner cone…

do not let it burndo not let it burn Record color of flameRecord color of flame

The MetalsThe Metals

Sodium - Sodium - NaNaClCl Potassium - Potassium - KKClCl Strontium - Strontium - SrSr(NO(NO33))22

Lithium - Lithium - LiLiNONO33

Calcium - Calcium - CaCaClCl22

Unknown: A, B, C or DUnknown: A, B, C or D

Emission SpectroscopyEmission Spectroscopy

Technique used to identify unknown Technique used to identify unknown elements in a sampleelements in a sample

Basis of TestBasis of Test

Electrons in the ground state get excited Electrons in the ground state get excited when energizedwhen energized

Excited electrons are unstableExcited electrons are unstable Electrons fall back down to the ground state Electrons fall back down to the ground state

by releasing energyby releasing energy Energy takes the form of visible lightEnergy takes the form of visible light

Line SpectrumLine Spectrum

Characteristic wavelengths (colors) of light are Characteristic wavelengths (colors) of light are given off by elementsgiven off by elements

These wavelengths are an elements line spectrumThese wavelengths are an elements line spectrum HydrogenHydrogen

410 nm

434 nm

486 nm

656 nm

Flame TestFlame Test

Used to identify metals in solutionUsed to identify metals in solution Electrons absorb energy from the flame to Electrons absorb energy from the flame to

enter the excited stateenter the excited state

SafetySafety

Goggles and apronsGoggles and aprons Double cone flameDouble cone flame Garbage in tin can Garbage in tin can

partially filled with partially filled with waterwater

Wash hands and lab Wash hands and lab stationstation

Bohr’s ModelBohr’s Model Electrons move like planets around the Electrons move like planets around the

sun.sun. In circular orbits at different levels.In circular orbits at different levels. Amounts of energy separate one level Amounts of energy separate one level

from another.from another.

III. The Bohr Model of the AtomIII. The Bohr Model of the Atom

A.A. Electrons of hydrogen circle the Electrons of hydrogen circle the nucleus in orbitsnucleus in orbits

1. 1. orbitsorbits have a fixed amount of energy have a fixed amount of energy

in the ground statein the ground state

2. 2. orbitsorbits are a fixed distance from the are a fixed distance from the

nucleusnucleus

3.3. orbitsorbits furthest from the nucleus have furthest from the nucleus have

the greatest energythe greatest energy

4. Electrons in the 4. Electrons in the ground stateground state can absorb can absorb quanta of energy – become quanta of energy – become excitedexcited- and - and move to a higher orbitmove to a higher orbit

5. Electrons emit 5. Electrons emit quantaquanta of energy when of energy when

they return to the ground statethey return to the ground state

6. Model applies only to hydrogen atoms 6. Model applies only to hydrogen atoms

Niels Bohr Niels Bohr (1885 – 1962) Bohr Model of the Atom(1885 – 1962) Bohr Model of the Atom

BohrBohr

c.The electron must be in one orbit or c.The electron must be in one orbit or another – it cannot be in between- the another – it cannot be in between- the energy is quantizedenergy is quantized

d. Line spectrum- produced when an d. Line spectrum- produced when an electron drops from a higher energy orbit electron drops from a higher energy orbit to a lower energy orbitto a lower energy orbit

i. A photon is emitted with energy E=hv i. A photon is emitted with energy E=hv equals difference in energy between equals difference in energy between the initial higher level and the final the initial higher level and the final lower orbitlower orbit

I. BOHRI. BOHR

A. Niels Bohr(1885-1962) – Danish A. Niels Bohr(1885-1962) – Danish physicist- worked with Rutherfordphysicist- worked with Rutherford

1.1. Electron circles the nucleus in orbitsElectron circles the nucleus in orbitsa. The closer the orbit to the nucleus the lower the energy a. The closer the orbit to the nucleus the lower the energy

level.level.

b. The total energy of the electron increases as the distance b. The total energy of the electron increases as the distance from the nucleus increasesfrom the nucleus increases

Lyman, Balmer, Paschen Series for HydrogenLyman, Balmer, Paschen Series for Hydrogen

Bohr’s ModelBohr’s Model

Nucleus

Electron

Orbit

Energy Levels

Bohr’s ModelBohr’s ModelIn

crea

sing

ene

rgy

Nucleus

First

Second

Third

Fourth

Fifth

} Further away from Further away from

the nucleus the nucleus means more means more energy.energy.

There is no “in There is no “in between” energybetween” energy

Energy LevelsEnergy Levels

BohrBohr

Make a model of Bohr’s Hydrogen. Bohr Make a model of Bohr’s Hydrogen. Bohr was only correct about Hydrogen.was only correct about Hydrogen.

Draw a nucleus Draw a nucleus Use the radius in book move decimal one Use the radius in book move decimal one

space to rightspace to right Measure in centimetersMeasure in centimeters Use markers to illustrate the excited vs Use markers to illustrate the excited vs

ground state electrons.ground state electrons.

Where the electron startsWhere the electron starts

The energy level and electron starts from is The energy level and electron starts from is called its ground state.called its ground state.

As it absorbs energy it goes up to an excited As it absorbs energy it goes up to an excited state energy level.state energy level.

Was each level equally distant from the Was each level equally distant from the other?other?

Then what happens?Then what happens?

Changing the energyChanging the energy Let’s look at a hydrogen atomLet’s look at a hydrogen atom

Changing the energy Heat or electricity or light can move the Heat or electricity or light can move the

electron up energy levelselectron up energy levels

Changing the energy As the electron falls back to ground state it As the electron falls back to ground state it

gives the energy back as lightgives the energy back as light

May fall down in stepsMay fall down in steps Each with a different energyEach with a different energy

Changing the energy

Further they fall, more energy, higher Further they fall, more energy, higher frequency.frequency.

This is simplifiedThis is simplified the orbitals also have different energies inside the orbitals also have different energies inside

energy levelsenergy levels All the electrons can move around.All the electrons can move around.

Complete Bohr model from the previous lessonComplete Bohr model from the previous lesson

Ultraviolet Visible Infrared

IV. Quantum Model of the AtomIV. Quantum Model of the Atom

A.A. Problem With the Bohr ModelProblem With the Bohr Model – Why – Why could the electron in hydrogen orbit in could the electron in hydrogen orbit in only a small number of allowed paths?only a small number of allowed paths?

BB. . Solving the ProblemSolving the Problem

1. 1. Louis de BroglieLouis de Broglie – electrons have a – electrons have a

dual naturedual nature - they can act like - they can act like

particles or waves !!!particles or waves !!!

Diffraction Patterns Diffraction Patterns x-rays through Al electrons through Al x-rays through Al electrons through Al

2. 2. SchrodingerSchrodinger – developed equations – developed equations

that treat electrons in atoms like wavesthat treat electrons in atoms like waves

a. describe the shapes of the a. describe the shapes of the orbitalsorbitals

in which electrons have a highin which electrons have a high

probability of being foundprobability of being found

b. b. quantum theoryquantum theory – mathematical – mathematical

explanation for the wave propertiesexplanation for the wave properties

of electrons that apply to all atomsof electrons that apply to all atoms

Louis de Broglie Erwin SchrodingerLouis de Broglie Erwin Schrodinger (1892-1987) (1887-1961) (1892-1987) (1887-1961)

Electrons have a dual Schrodinger equationElectrons have a dual Schrodinger equationnature (particle + wave) describes wave nature (particle + wave) describes wave

properties of electronsproperties of electrons mathematicallymathematically

I. Quantum model of the atomI. Quantum model of the atom

A.A. Louis DeBroglie- (1892-1987) French physicistLouis DeBroglie- (1892-1987) French physicist1.1. Electrons have a wave/ particle nature –so if light is Electrons have a wave/ particle nature –so if light is

passed through a slit – wave interference occurs- proved passed through a slit – wave interference occurs- proved by the equation (1924)by the equation (1924)

Wavelength = Planck’s constant/mass times velocityWavelength = Planck’s constant/mass times velocity

If all moving objects have wave characteristics why don’t we If all moving objects have wave characteristics why don’t we see ourselves waving?see ourselves waving?

Everybody – stadium waveEverybody – stadium wave

Matter is a WaveMatter is a Wave Does not apply to large objectsDoes not apply to large objects Things bigger then an atomThings bigger then an atom

A baseball has a wavelength of about 10A baseball has a wavelength of about 10--32 32

m when moving 30 m/s m when moving 30 m/s

An electron at the same speed has a An electron at the same speed has a

wavelength of 10wavelength of 10--3 3 cmcm

Big enough to measure. Big enough to measure.

The physics of the very smallThe physics of the very small Quantum mechanics explains how the very Quantum mechanics explains how the very

small behaves.small behaves. Classic physics is what you get when you Classic physics is what you get when you

add up the effects of millions of packages.add up the effects of millions of packages. Quantum mechanics is based on probability Quantum mechanics is based on probability

II.Heisenberg Uncertainty II.Heisenberg Uncertainty PrinciplePrinciple

It is impossible to know exactly the position It is impossible to know exactly the position and velocity of a particle at the same time.and velocity of a particle at the same time.

The better we know one, the less we know The better we know one, the less we know the other.the other.

The act of measuring changes the The act of measuring changes the properties.properties.

Look at the fanLook at the fan

More obvious with the very More obvious with the very smallsmall

To measure where a electron is, we use light.To measure where a electron is, we use light. But the light moves the electronBut the light moves the electron And hitting the electron changes the frequency of the light.And hitting the electron changes the frequency of the light.

Watch the balloonWatch the balloon

Moving Electron

Photon

Before

ElectronChanges velocity

Photon changes wavelength

After

C.C. Principles of the Quantum ModelPrinciples of the Quantum Model

1. electrons act like waves1. electrons act like waves

2. probability of an electron being found 2. probability of an electron being found

at various distances from the nucleus at various distances from the nucleus

3. 3. orbitalsorbitals – a 3-D region about the – a 3-D region about the

nucleus where a specific electron maynucleus where a specific electron may

be foundbe found

4. electrons have greater energy as their 4. electrons have greater energy as their

distance from the nucleus increasesdistance from the nucleus increases

5. energies of 5. energies of orbitalsorbitals are quantized within are quantized within

main energy levelsmain energy levels

6. the exact location of electrons can not 6. the exact location of electrons can not

be pinpointed – they are found in regions be pinpointed – they are found in regions

of high probability called of high probability called orbitalsorbitals or or

electron cloudselectron clouds

Quantum Atomic ModelQuantum Atomic Model

Similarities between Bohr and SchrodingerSimilarities between Bohr and Schrodinger– 1. the closer the orbital to the nucleus the lower 1. the closer the orbital to the nucleus the lower

the energythe energy– 2. to move from a lower to a higher level the 2. to move from a lower to a higher level the

energy absorbed must be equal to the energy absorbed must be equal to the difference between the levelsdifference between the levels

Quantum Model Quantum Model

3.When e- drops from a a higher to lower 3.When e- drops from a a higher to lower level electromagnetic radiation is emitted level electromagnetic radiation is emitted =difference in energy levels=difference in energy levels

4. the most probable location of the (H) e- is 4. the most probable location of the (H) e- is a distance equal to Bohr’s lowest energy a distance equal to Bohr’s lowest energy level.level.

Atomic OrbitalsAtomic Orbitals Principal Quantum Number (n) = the Principal Quantum Number (n) = the

energy level of the electron.energy level of the electron. Within each energy level the complex Within each energy level the complex

math of Schrodinger’s equation describes math of Schrodinger’s equation describes several shapes.several shapes.

These are called atomic orbitalsThese are called atomic orbitals Regions where there is a high probability Regions where there is a high probability

of finding an electron. 90%of finding an electron. 90%

Orbitals (s, p, d, f)Orbitals (s, p, d, f)

Orbitals (s, p, d types)Orbitals (s, p, d types)

s orbitalss orbitals

(one type)(one type)

p orbitalsp orbitals

(3 types)(3 types)

d orbitalsd orbitals

( 5 types)( 5 types)

Orbitals in Sodium (Na)Orbitals in Sodium (Na)

1 s orbital for every 1 s orbital for every energy levelenergy level Spherical Spherical

shapedshaped

Each s orbital can hold 2 electronsEach s orbital can hold 2 electrons Called the 1s, 2s, 3s, etc.. orbitals.Called the 1s, 2s, 3s, etc.. orbitals.

S orbitalsS orbitals

P orbitalsP orbitals Start at the second energy level Start at the second energy level 3 different directions3 different directions 3 different shapes3 different shapes Each can hold 2 electronsEach can hold 2 electrons

P OrbitalsP Orbitals

D orbitalsD orbitals Start at the third energy level Start at the third energy level 5 different shapes5 different shapes Each can hold 2 electronsEach can hold 2 electrons

http://www.falstad.com/qmatom/

http://www.falstad.com/qmatom/

F orbitalsF orbitals Start at the fourth energy levelStart at the fourth energy level Have seven different shapesHave seven different shapes 2 electrons per shape2 electrons per shape

F orbitalsF orbitals

SummarySummary

s

p

d

f

# of shapes

Max electrons

Starts at energy level

1 2 1

3 6 2

5 10 3

7 14 4

V. Quantum NumbersV. Quantum Numbers

A.A. Principal Quantum NumberPrincipal Quantum Number

1. main energy level 1. main energy level

BB. . Orbital Quantum NumberOrbital Quantum Number (sublevel) (sublevel)

1. shape of orbital (s,p,d,f) 1. shape of orbital (s,p,d,f)

C. Magnetic Quantum NumberC. Magnetic Quantum Number

1. orientation of orbital about the nucleus1. orientation of orbital about the nucleus

D. Spin Quantum NumberD. Spin Quantum Number

1.indicates clockwise or counter-1.indicates clockwise or counter-

clockwise spin of the electron (+ or – ½) clockwise spin of the electron (+ or – ½)

Four Quantum NumbersFour Quantum NumbersA.Principal Quantum Number (n) main energy level

B. Orbital Quantum Number (l) shape of orbital (s, p, d, f)

C. Magnetic Quantum Number (m) orientation of orbital about the nucleus

D. Spin Quantum Number (s) indicates clockwise or counter-clockwise spin of

the electron (+½ or –½)

Create a model of sub-atomic levelsCreate a model of sub-atomic levels

By Energy LevelBy Energy Level First Energy LevelFirst Energy Level only s orbitalonly s orbital only 2 electronsonly 2 electrons 1s1s22

Second Energy LevelSecond Energy Level s and p orbitals are s and p orbitals are

availableavailable 2 in s, 6 in p2 in s, 6 in p 2s2s222p2p66

8 total electrons8 total electrons

By Energy LevelBy Energy Level Third energy levelThird energy level s, p, and d orbitalss, p, and d orbitals 2 in s, 6 in p, and 10 2 in s, 6 in p, and 10

in din d 3s3s223p3p663d3d1010


Fourth energy levelFourth energy level s,p,d, and f orbitalss,p,d, and f orbitals 2 in s, 6 in p, 10 in d, 2 in s, 6 in p, 10 in d,

ahd 14 in fahd 14 in f 4s4s224p4p664d4d10104f4f1414


By Energy LevelBy Energy Level Any more than the Any more than the

fourth and not all the fourth and not all the orbitals will fill up.orbitals will fill up.

You simply run out of You simply run out of electronselectrons

The orbitals do not fill The orbitals do not fill up in a neat order.up in a neat order.

The energy levels The energy levels overlapoverlap

Lowest energy fill Lowest energy fill first.first.

Incr

easi

ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

I.Electron ConfigurationsI.Electron Configurations A. The way electrons are arranged in A. The way electrons are arranged in

atoms.atoms. 1..Aufbau principle1..Aufbau principle- electrons enter the - electrons enter the

lowest energy first.lowest energy first. 2.This causes difficulties because of the 2.This causes difficulties because of the

overlap of orbitals of different energies.overlap of orbitals of different energies. B.Pauli Exclusion PrincipleB.Pauli Exclusion Principle- at most 2 - at most 2

electrons per orbital - different spinselectrons per orbital - different spins

Electron ConfigurationElectron Configuration C. Hund’s RuleC. Hund’s Rule- When electrons occupy - When electrons occupy

orbitals of equal energy they don’t pair up orbitals of equal energy they don’t pair up until they have to .until they have to .

Let’s determine the electron configuration Let’s determine the electron configuration for Phosporus for Phosporus

Need to account for 15 electronsNeed to account for 15 electrons

The first two electrons The first two electrons go into the 1s orbitalgo into the 1s orbital

Notice the opposite Notice the opposite spinsspins

only 13 moreonly 13 moreIncr

easi

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nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

The next electrons go The next electrons go into the 2s orbitalinto the 2s orbital

only 11 moreonly 11 more

Incr

easi

ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

• The next electrons go into the 2p orbital

• only 5 more

Incr

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ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

• The next electrons go into the 3s orbital

• only 3 more

Incr

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ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

Incr

easi

ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

• The last three electrons go into the 3p orbitals.

• They each go into separate shapes

• 3 unpaired electrons

• 1s22s22p63s23p3

The easy way to remember The easy way to remember

1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2

• 2 electrons

Fill from the bottom up Fill from the bottom up following the arrowsfollowing the arrows

1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2

• 4 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

• 12 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

3p6 4s2

• 20 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

3p6 4s2 3d10 4p6

5s2

• 38 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

3p6 4s2 3d10 4p6

5s2 4d10 5p6 6s2

• 56 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

3p6 4s2 3d10 4p6

5s2 4d10 5p6 6s2

4f14 5d10 6p6 7s2

• 88 electrons


1s2s 2p3s 3p 3d4s 4p 4d 4f

5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f

• 1s2 2s2 2p6 3s2

3p6 4s2 3d10 4p6

5s2 4d10 5p6 6s2

4f14 5d10 6p6 7s2

5f14 6d10 7p6 • 108 electrons

Write these electron Write these electron configurationsconfigurations

Titanium - 22 electronsTitanium - 22 electrons 1s1s222s2s222p2p663s3s223p3p664s4s223d3d22

Vanadium - 23 electrons Vanadium - 23 electrons 1s1s222s2s222p2p663s3s223p3p664s4s223d3d33

Chromium - 24 electronsChromium - 24 electrons 1s1s222s2s222p2p663s3s223p3p664s4s223d3d4 4 is expectedis expected But this is wrong!!But this is wrong!!

Exceptions to Electron Exceptions to Electron ConfigurationConfiguration

Orbitals fill in order Orbitals fill in order Lowest energy to higher energy.Lowest energy to higher energy. Adding electrons can change the energy of Adding electrons can change the energy of

the orbital.the orbital. Half filled orbitals have a lower energy.Half filled orbitals have a lower energy. Makes them more stable.Makes them more stable. Changes the filling orderChanges the filling order

Chromium is actuallyChromium is actually 1s1s222s2s222p2p663s3s223p3p664s4s113d3d55

Why?Why? This gives us two half filled orbitals.This gives us two half filled orbitals. Slightly lower in energy.Slightly lower in energy. The same principal applies to copper.The same principal applies to copper.

Copper’s electron Copper’s electron configurationconfiguration

Copper has 29 electrons so we expectCopper has 29 electrons so we expect 1s1s222s2s222p2p663s3s223p3p664s4s223d3d99

But the actual configuration isBut the actual configuration is 1s1s222s2s222p2p663s3s223p3p664s4s113d3d1010

This gives one filled orbital and one half This gives one filled orbital and one half filled orbital.filled orbital.

Remember these exceptionsRemember these exceptions

Valence ElectronsValence Electrons

I. Valence electrons are defined as electrons I. Valence electrons are defined as electrons located in the highest occupied energy level of an located in the highest occupied energy level of an atom.atom.

A. Inner electrons are not shown.A. Inner electrons are not shown.1. inner electrons are not part of the bonding relationship 1. inner electrons are not part of the bonding relationship between elementsbetween elements

B.Electron dot structure- show the symbol of an element with dots B.Electron dot structure- show the symbol of an element with dots to represent the electrons on the highest energy levelto represent the electrons on the highest energy level

1. G.N. Lewis- American chemist (1875-1946) – devised the 1. G.N. Lewis- American chemist (1875-1946) – devised the method method

The Lewis dot structure for Oxygen

OOxygen is in group VIA so it has 6 valence electrons

The Lewis dot structure for Chlorine

Clchlorine is in group VIIA so it has 7 valence electrons

The Lewis dot structure for calcium

Cacalcium is in group IIA so it has 2 valence electrons

Lewis dot structure of a compound

NH3

1) How many valence electrons does N have?N is in group VA so it has 5 valence electrons

2) How many valence electrons does H have? H is in group IA so each H has one valence electron

3) How many valence electrons does Neon have.

Making calcium chloride

+Ca Cl Cl

Ca( Cl )2

Lewis dot structure of a compound

NH3

N

H

H

H

Lewis dot structure and making ammonium ion

NH4+

H+

H

N H

H

H

+

Orbitals (s, p, d, f)Orbitals (s, p, d, f)

Orbitals (s, p, d types)Orbitals (s, p, d types)

s orbitalss orbitals

(one type)(one type)

p orbitalsp orbitals

(3 types)(3 types)

d orbitalsd orbitals

( 5 types)( 5 types)

Orbitals in Sodium (Na)Orbitals in Sodium (Na)

C.C. Principles of the Quantum ModelPrinciples of the Quantum Model

1. electrons act like waves1. electrons act like waves

2. probability of an electron being found 2. probability of an electron being found

at various distances from the nucleus at various distances from the nucleus

3. 3. orbitalsorbitals – a 3-D region about the – a 3-D region about the

nucleus where a specific electron maynucleus where a specific electron may

be foundbe found

4. electrons have greater energy as their 4. electrons have greater energy as their

distance from the nucleus increasesdistance from the nucleus increases

5. energies of 5. energies of orbitalsorbitals are quantized within are quantized within

main energy levelsmain energy levels

6. the exact location of electrons can not 6. the exact location of electrons can not

be pinpointed – they are found in regions be pinpointed – they are found in regions

of high probability called of high probability called orbitalsorbitals or or

electron cloudselectron clouds

VI. Determining Number of Orbital VI. Determining Number of Orbital Types and ElectronsTypes and Electrons

A.A. If If nn = the number of the principal energy= the number of the principal energy

level or shell ( 1-7) and there is a maximumlevel or shell ( 1-7) and there is a maximum

of 2 electrons per orbital then: of 2 electrons per orbital then:

1.1. n n = the possible number of orbital types = the possible number of orbital types

for that shellfor that shell

2. 2. nn22 = total number or orbitals possible = total number or orbitals possible

3. 3. 2n2n22 = total number of electrons possible = total number of electrons possible

4. Heisenberg Uncertainty Werner Heisenberg4. Heisenberg Uncertainty Werner HeisenbergPrinciple (1901-1976)Principle (1901-1976)

Both the velocity and Both the velocity and position of a particle position of a particle (electron) can not be (electron) can not be measured at the measured at the same timesame time

B.B. ExamplesExamplesIf n = 3 then in energy level 3:If n = 3 then in energy level 3: 33 orbital types possible (s,p,d) orbital types possible (s,p,d) (n)(n) 9 9 orbitals are possible orbitals are possible (n(n22)) 1818 electrons are possible electrons are possible (2n(2n22))

If n = 4 then in energy level 4:If n = 4 then in energy level 4: 44 orbital types possible (s,p,d,f) orbital types possible (s,p,d,f) (n)(n) 16 16 orbitals are possible orbitals are possible (n(n22)) 3232 electrons are possible electrons are possible (2n(2n22))

VII. Electron Configuration VII. Electron Configuration

A. RulesA. Rules and Principlesand Principles

1. 1. Aufbau PrincipleAufbau Principle – an electron – an electron

occupies the lowest energy orbital that can occupies the lowest energy orbital that can receive itreceive it

2. 2. Hund’s RuleHund’s Rule – orbitals of equal energy are – orbitals of equal energy are each occupied by one electron before any each occupied by one electron before any orbital is occupied by a second electronorbital is occupied by a second electron

3. 3. Pauli Exclusion PrinciplePauli Exclusion Principle – no two electrons – no two electrons in the same atom can have the same set in the same atom can have the same set of four quantum numbersof four quantum numbers

B. Types of Electron ConfigurationsB. Types of Electron Configurations

1. Electron –configuration notation1. Electron –configuration notation

a. indicates number of the principala. indicates number of the principal

energy level, the orbitals, and energy level, the orbitals, and

the number of electrons possiblethe number of electrons possible

2. Orbital Notation2. Orbital Notation – arrows indicate location – arrows indicate location and spin of electronsand spin of electrons

3. Electron-dot structure3. Electron-dot structure – indicates valence – indicates valence shell electrons shell electrons

Chapter 5 Electrons in Atoms Light and quantized energy.

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Transcript of Chapter 5 Electrons in Atoms Light and quantized energy.