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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’
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.
Low intensity blue, however, could.
e-1
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.
Low intensity blue, however, could. Violet also liberated electrons and gave a little KE to them.
e-1
e-1
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.
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?
Ch27 HW#1 1 – 51. How much energy for blue light that has a frequency of
6.3 x 1014 Hz.
E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J
2. What is the energy of a 1m long radio wave?
3. What is the energy of an Xray with wavelength = 1x10-10m?
Ch27 HW#1 1 – 51. How much energy for blue light that has a frequency of
6.3 x 1014 Hz.
E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J
2. What is the energy of a 1m long radio wave?
3. What is the energy of an Xray with wavelength = 1x10-10m?
Jxm
xxchE 25
834
1099.11
)103)(106.6(
Ch27 HW#1 1 – 51. How much energy for blue light that has a frequency of
6.3 x 1014 Hz.
E = h.f = (6.626x10-34J.s)(6.3x1014Hz) = 4.2x10-19J
2. What is the energy of a 1m long radio wave?
3. What is the energy of an Xray with wavelength = 1x10-10m?
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,
how much energy does the electron leave with?
a.
b.
c.
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,
how much energy does the electron leave with?
a.
b.
c.
Hzxmx
xcf s
m14
9
8
107.910310
)103(
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,
how much energy does the electron leave with?
a.
b. E = h.f = (6.626x10-34J.s)(9.7x1014Hz) = 6.4x10-19J
c.
Hzxmx
xcf s
m14
9
8
107.910310
)103(
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,
how much energy does the electron leave with?
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,
how much energy does the electron leave with?
a.
b.
5. Cesium has a work function of 1.96eV. a. What is the threshold wavelength?c. If 425nm violet light interacts with the electron,
how much energy does the electron leave with?
a.
b.
nmJx
xx
E
ch
JxeV
JxeV
633101.3
)103)(106.6(
101.31
106.196.1
19
834
1919
5. Cesium has a work function of 1.96eV. a. What is the threshold wavelength?c. If 425nm violet light interacts with the electron,
how much energy does the electron leave with?
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.
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
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
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?
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
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
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)