Ch27.1 – Quantum Theory Diffraction - bending of waves around barriers. One proof light is a wave....

$: Ch27.1 – Quantum Theory Diffraction - bending of waves around barriers. One proof light is a wave. Double Slit Interference Light of wavelength λ.$
Ch27.1 – Quantum TheoryDiffraction - bending of waves around barriers. One proof light is a wave.

Double Slit InterferenceLight of wavelength λ

Photoelectric effect - (Einstein’s Nobel Prize)Classic theory: Light is an E/M wave. So even low energy light, with high intensity should liberate electrons

from “special” surface. Red light didn’t liberate any electrons.

‘special metal surface’



Low intensity blue, however, could.

e-1



Low intensity blue, however, could. Violet also liberated electrons and gave a little KE to them.

e-1

e-1



Low intensity blue, however, could. Violet also liberated electrons and gave a little KE to them.Einstein explained: “Energy is quantized.” Comes in the form of photons

- little bundles of energy. Red photons low energy photons. Blue photons higher energy photons. (Higher frequency = Higher energy) e-1

E = h.f

e-1

Energy Equations:

E = h.f

Planck’s Constant: h = 6.626x10-34J.s

The energy required to remove an electron is called the work function.

E = h.fo

1 electron-Volt (eV) = 1.6x10-19 Joules (J)

When the electron is hit by a high energy photon, the electron will ejectfrom the atom and leave with the extra energy:

extra energy energy of photon work function of atom

ch

E

ophoton EEKE

Ex1) A photon of red light has a frequency of 400 x 1012 Hz. What is its energy in joules?

Ex2) What is the energy of a 500nm green photon?

Ex1) A photon of red light has a frequency of 400 x 1012 Hz. What is its energy in joules?

E = h.f = (6.626x10-34J.s)(400x1012Hz) = 2.65x10-19J

Ex2) What is the energy of a 500nm green photon?

eVJx

eVJx

Jxx

xxchE

5.2106.1

11098.3

1098.310500

)103)(106.6(

19

19

199

834

Ex3) Sodium has a threshold wavelength of 536nm. a. What is the frequency?b. What is the work function?c. If 348nm UV light interacts with the electron,

how much energy does the electron leave with?

Ionization Energy (Work function)

e-1

nucleus

Ch27 HW#1 1 – 5

Ch27 HW#1 1 – 51. How much energy for blue light that has a frequency of

6.3 x 1014 Hz.

2. What is the energy of a 1m long radio wave?

3. What is the energy of an Xray with wavelength = 1x10-10m?


6.3 x 1014 Hz.

E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J




6.3 x 1014 Hz.

E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J



Jxm

xxchE 25

834

1099.11

)103)(106.6(


6.3 x 1014 Hz.

E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J



Jxm

xxchE 25

834

1099.11

)103)(106.6(

Jxmx

xxchE 15

10

834

1099.1101

)103)(106.6(

4. Zinc has a threshold wavelength of 310nm. a. What is the frequency?b. What is the work function?c. If 240nm UV light interacts with the electron,


a.

b.

c.



a.

b.

c.

Hzxmx

xcf s

m14

9

8

107.910310

)103(



a.

b. E = h.f = (6.626x10-34J.s)(9.7x1014Hz) = 6.4x10-19J

c.

Hzxmx

xcf s

m14

9

8

107.910310

)103(



a.

b. E = h.f = (6.626x10-34J.s)(9.7x1014Hz) = 6.4x10-19J

c.

Hzxmx

xcf s

m14

9

8

107.910310

)103(

JxJxJxEEKE

Jxmx

xxchE

oUV

UV

191919

199

834

109.1104.6103.8

103.810240

)103)(106.6(

5. Cesium has a work function of 1.96eV. a. What is the threshold wavelength?c. If 425nm violet light interacts with the electron,


a.

b.



a.

b.

nmJx

xx

E

ch

JxeV

JxeV

633101.3

)103)(106.6(

101.31

106.196.1

19

834

1919



a.

b.

JxJxJxEEKE

Jxmx

xxchE

oviolet

violet

191919

199

834

106.1101.3107.4

107.410425

)103)(106.6(

nmJx

xx

E

ch

JxeV

JxeV

633101.3

)103)(106.6(

101.31

106.196.1

19

834

1919

Ch27.2 – Wave Nature of Particles- by 1920’s proven that light acts as particle and a wave.

E/M radiation’s “wave/particle duality” De Broglie thought this might be characteristic of all things

If the photons of E/M radiation travel as transverse wavesand exhibit particle behaviors,

then matter in motion must exhibit wave behaviorDeBroglie Wavelength:

momentum

Ex1) Calculate the wavelength of a baseball (m = 0.25kg) hit at 21 m/s.

Ex2) Calculate the wavelength of an electron traveling at half the speed of light.

(r = 0.053nm)

p

h

mv

h

Ch27.2 – Wave Nature of Particles- by 1920’s proven that light acts as particle and a wave.

E/M radiation’s “wave/particle duality” De Broglie thought this might be characteristic of all things

If the photons of E/M radiation travel as transverse wavesand exhibit particle behaviors,

then matter in motion must exhibit wave behaviorDeBroglie Wavelength:

momentum

Ex1) Calculate the wavelength of a baseball (m = 0.25kg) hit at 21 m/s.

Ex2) Calculate the wavelength of an electron traveling at half the speed of light.

(r = 0.053nm)

p

h

mv

h

m103.1 )21)(25(.

10626.6 34

34

xkg

sJx

mv

h

sm

m105.1

)105)(101.9(

10626.6

10

631

34

x

xkgx

sJx

mv

h

sm

Heisenberg’s Uncertainty PrincipleElectrons are so small, you can’t know both their location and

momentum. If you know its location, you don’t know where its going.If you know where it’s going, you won’t know where it is along its path.

Ch27 HW#2 6 – 9

Ch27 HW#2 6 – 96) I have a mass of 75kg walking at 1 m/s. Find De Broglie λ.

7) An electron (m=9.11x10-31kg) with speed of 4.3x106 m/s. Find λ.



m108.8 )1)(75(

10626.6 36

34

xkg

sJx

mv

h

sm



m108.8 )1)(75(

10626.6 36

34

xkg

sJx

mv

h

sm

m107.1

)103.4)(101.9(

10626.6

10

631

34

x

xkgx

sJx

mv

h

sm

8) A 7.0kg bowling ball rolls with a velocity of 8.5 m/s. a) Find λ.

b) Why don’t we see it wiggle?

9) X-ray has a wavelength of 5.0x10-12m. a) calc its mass

b) why does it exhibit little particle behavior?





m101.1 )5.8)(7(

10626.6 36

34

xkg

sJx

mv

h

sm





m101.1 )5.8)(7(

10626.6 36

34

xkg

sJx

mv

h

sm

kg104.4

)103)(105(

10626.6

31

812

34

xm

xmx

sJx

v

hm

sm

Ch28.1 – The AtomHistory:1800’s – Millikan’s Oil Drop Experiment found the charge

of an electron. - Cathode Ray Tube – found electron mass1900’s – JJ Thompson’s Plum Pudding Model of the atom - Rutherford’s Gold Foil Experiment (1905)

Atoms are mostly empty space with a dense core, called it nucleus. - Bohr’s Planetary Model of the atom

Electrons have discrete energy levels and cannot be found in between. They can only absorb 1 photon, jump to excited state, return and release photons.

- Current model: have a wiggle and energy levels are complicated paths.

Ex1) An electron in an excited state of the hydrogen atom drops from the second energy level to the first, as shown. Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 13.6eV E1 = 3.4eV

a)

b)

c)

Ex1) An electron in an excited state of the hydrogen atom drops from the second energy level to the first, as shown. Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 13.6eV E1 = 3.4eV

a) 13.6 – 3.4 = 10.2eV

b)

c)

JxeV

JxeV 1819

106.11

106.12.10

HzxJsx

Jx

h

Ef 15

34

18

104.2106.6

106.1

mxx

x

f

c

s

sm

7

115

8

1022.1104.2

103

HW #2) An electron in an excited state of Mercury drops from 8.82eVto 6.67eV.

Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 8.82eV E1 = 6.67eV

Ch28 HW#1 1 – 5

HW #2) An electron in an excited state of Mercury drops from 8.82eVto 6.67eV.

Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 8.82eV E1 = 6.67eV

a) E = 8.82 – 6.67 = 2.15eV

b)

Ch28 HW#1 1 – 5

JxeV

JxeV 1819

1044.31

106.115.2

HzxJsx

Jx

h

Ef 14

34

18

102.5106.6

1044.3

mxx

x

f

c

s

sm

7

114

8

106.5102.5

103

Lab 28.1 – Atomic Spectra

- due tomorrow

- Ch18 HW#1 due at beginning of period

Ch28 HW#1 1 – 5 1. The diameter of the hydrogen nucleus is 2.5x10-15m and the distance to the first energy level is ~ 5x10-9m. If a baseball has a diam of 7.5cmand it represents the nucleus, how far away would the first energy level be?

1B1H n

baseball of Diam

n

nuc H of Diam

Ch28 HW#1 1 – 5 1. The diameter of the hydrogen nucleus is 2.5x10-15m and the distance to the first energy level is ~ 5x10-9m. If a baseball has a diam of 7.5cmand it represents the nucleus, how far away would the first energy level be?

mm

m

m000,150n

n

0.075

5x10

2.5x10

n

baseball of Diam

n

nuc H of Diam

11B

9-

15-

1B1H

3. An electron in H drops from 11.6eV to 5.1eV. Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 11.6eV E1 = 5.1eV

a) 11.6 – 5.1 = 6.5eV

b) (E=hf)

c) (c=λf)

3. An electron in H drops from 11.6eV to 5.1eV. Calc the energy, frequency, and wavelength of the photon released.

e-1 E2 = 11.6eV E1 = 5.1eV

a) 11.6 – 5.1 = 6.5eV

b) (E=hf)

c) (c=λf)

JxeV

JxeV 1819

1004.11

106.15.6

HzxJsx

Jx

h

Ef 15

34

18

106.1106.6

1004.1

mxx

x

f

c

s

sm

7

115

8

1091.1106.1

103

4. Emitted photon is orange at 600nm. Calc frequency and energy.

a) (c=λf)

b) (E=hf)

4. Emitted photon is orange at 600nm. Calc frequency and energy.

a) (c=λf)

b) (E=hf) JxHzxJsxhfE 191434 103.3105106.6

Hzxmx

xcf s

m14

9

8

10510600

103

5. Emitted photon is blue-green at 490nm. Calc frequency and energy.

a) (c=λf)

b) (E=hf)

5. Emitted photon is blue-green at 490nm. Calc frequency and energy.

a) (c=λf)

b) (E=hf) JxHzxJsxhfE 191434 101.4101.6106.6

Hzxmx

xcf s

m14

9

8

101.610490

103

Ch30.1 – The NucleusAtomic particles: Location Charge Mass

Proton Inside nucleus (+1) 1 a.m.u.Neutron Inside nucleus (0) 1 a.m.u.Electron Outside nucleus (+1) 0.0005 a.m.u.

Atoms radius ~ 10–10m, nucleus is 10,000 times smaller

yet 99.9% of mass is there- density of nucleus = 2.3x1017 kg/m3

- nuclides act like a swarm of beesWhat holds it together?

v v

Ch30.1 – The NucleusAtomic particles: Location Charge Mass

Proton Inside nucleus (+1) 1 a.m.u.Neutron Inside nucleus (0) 1 a.m.u.Electron Outside nucleus (+1) 0.0005 a.m.u.

Atoms radius ~ 10–10m, nucleus is 10,000 times smaller

yet 99.9% of mass is there- density of nucleus = 2.3x1017 kg/m3

- nuclides act like a swarm of beesWhat holds it together?

Strong Nuclear Force!- takes ~ 8,000,000 eV to remove a nucleon

(compare to removing an electron from H = 13.6 eV)Isotopes - same element (same # protons) differ in # of neutrons.Ex1) How many nuetrons in iron isotope: 56

26Fe?

Ex2) Write the symbol for chlorine-36.

v v

Radioactive DecayAlpha Decay – alpha particle emitted from nucleus (4

2He or 42α)

23892U 4

2α + ____ 42α are low energy

Beta Decay – beta particle emitted (0-1β or 0

-1e)

10n 1

1p + ____ 0-1β are mid energy

Gamma Decay – high energy photon released (γ)

Ex3) Write the eqn for the radioactive decay of Radium-226 that emits an alpha particle and becomes radon.

v v

Ex4) Write the eqn for the radioactive decay of lead-209 into bismuth-209.

Half Life – time it takes for half of a radioactive sample to decay:Exs: Hydrogen-3: 12.3 yrs

Carbon-14: 5730 yrsUranium-235: 710,000,000 yrs

Ex5) Half life of fluorine-17 is 66sec. If you have a 32g sample, how much will be left after 4min 24sec?

The Energy of Matter E = mc2

Ex6) How much energy is released if an electron of mass 9.11x10-31kg is completely turned into energy?

Nuclear fission – 1 atom breaks into smaller pieces

Nuclear fusion – nuclei combine together

Ch30 HW#1Ch30 HW#2Ch27-30 Rev

(No Rev day, test tomorrow)

Ch27.1 – Quantum Theory Diffraction - bending of waves around barriers. One proof light is a wave....

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