Download CHAPTER 4 ELECTROMAGNETIC RADIATION 1. TYPES 2

CHAPTER 4
ELECTROMAGNETIC RADIATION
1. TYPES
2. CHARACTERISTICS
a. TRAVEL THROUGH SPACE AS _____________
AT A SPEED OF _________________________
WAVELENGTH:
AMPLITUDE:
FREQUENCY:
b. EQUATION RELATING WAVELENGTH AND FREQUENCY:
1. WAVELENGTH AND FREQUENCY ARE
___________________ PROPORTIONAL
c. ENERGY IS EMITTED OR ABSORBED IN
_________________ OR _________________
(PLANCK’S THEORY)
d. EQUATION RELATING ENERGY AND FREQUENCY:
e. ENERGY AND FREQUENCY ARE
____________________ PROPORTIONAL
3. QUANTA ARE VERY SMALL. THEREFORE,
ENERGY ________________________________.
EX. 1: Infrared Radiation has a frequency of 4.25 x1013s-1. Find its wavelength.
Knowing the frequency of the light, calculate its energy.
2. A beam of light has a wavelength of 5.95 x 10-7 m. What is its frequency?
b. What type of electromagnetic radiation is it?
c. Calculate the energy of the radiation.
d. Express the wavelength in nanometers (nm).
NOTE: 1 m = 102 cm 1 m = 103 mm
1 m = 106 µm
1 m = 109 nm
3. The energy of a quantum is 15.5 x 10-15 J. What is the frequency of that quantum?
Practice Problems:
Name_________________________
Wavelength, Frequency, and Energy
The Wavelength Equation
Planck’s Theory
c=λ*f
E=h*f
λ = wavelength; m
f = frequency; s-1
8
c = speed of light; 3.00 x 10 m/s
E = Energy; J
h = Planck’s constant; 6.63 x 10-34 j-s
f = frequency; s-1
Formulas, setups, correct units, and correct sig figs must be
shown.
c
1. What is the frequency of violet light with a wavelength of
4.08 x 10-4 m?
c
2. What is the wavelength of the yellow sodium emission, which has a
frequency of 5.09 X 10 14 s-1?
3. The red spectral line of lithium occurs at 671 nm (Hint: What is this
in meters?).
a. Calculate the frequency of this spectral line.
b. Calculate the energy of a photon of this light.
4. Calculate the frequency of light with a wavelength of 4.78 x 10-7 m.
What type of electromagnetic energy is this light wave? (See p. 129)
5. What is the energy of a photon of radio waves with a frequency of
1.365 X 10 9 s-1?
6. A particular transition of the rubidium atom emits light whose
energy is 2.54 x 10-19 J. Calculate the frequency of this light.
PHOTOELECTRIC EFFECT
BRIGHT LINE SPECTRUM (Atomic emission spectrum)
1. 2. 3. When this light passes through a prism or spectroscope, it creates a
____________________spectrum.
4. Bright line spectrum:
5. This shows that THE ENERGIES OF ATOMS ARE QUANTIZED -
COMPTON EFFECT
1.
2.
DeBroglie: MATTER WAVES
1.
Equation:
b.
c.
BOHR EQUATION
Specifies the energies of a one electron atom
E = -2.178 x 10-18 J
n2
n = energy level
and, when the electron is changing energy levels,
Δ E = E final – E initial
(Principal quantum no.)
1. Calculate the energy of a Hydrogen electron occupying energy level 2 (n = 2).
2. Calculate the energy involved as a hydrogen electron falls from n = 4 to n = 2. Then
express that energy in kcal.
BOHR IN PRACTICE
1. 2. 3. QUANTUM NUMBER
BUT WAIT…
HEISENBERG’S UNCERTAINTY PRINCIPLE-
QUANTUM MECHANICAL MODEL
4 QUANTIUM NUMBERS:
1. 2. 3. 4. PRINCIPAL QUANTUM NUMBER
a.
b.
c. Maximum number of e- in outer level is ______, in the next outermost level,
______.
ORBITAL QUANTUM NUMBER
a.
b.
c.
d.
MAGNETIC QUANTUM NUMBER
a.
b.
c. SHAPES OF SUBLEVELS
s-
p-
d-
f-
SPIN QUANTUM NUMBER
a.
b.
ENERGY
LEVEL
SUBLEVELS
n=1
n=2
n=3
n=4
n=5
Same sublevels for n = 6, n = 7.
ORBITALS
per sublevel
ELECTRONS
per sublevel
ELECTRONS
per E level
(2n2)
3 MAIN GUIDELINES
1. Aufbau Principle-
2. Pauli Exclusion Principle-
3. Hund’s Rule-
ELECTRON CONFIGURATIONS
H:
He:
Li:
Be:
Al:
Ti:
The period number gives the number of occupied principal energy
levels.
Ex. Mg:
EXCITED STATES
1. 1s22s22p33s1: How do we know this is an excited state?
a. b. c. 2. 1s2 2p1: Why is this excited?
a. b. 3. 1s22s22p63s13p6
4. 1s22p63s23p5
5. 1s22s22p3
ORBITAL NOTATIONS
Carbon:
Sodium:
Outershell electrons: e- in outermost principal energy level
Ca:
Mg:
Group 2A:
Group 1A:
B:
Al:
Ga:
Group 3A:
Ne:
Ar:
Group 8A:
GENERALIZATION:
For the main group elements (A groups or s and p blocks),
PATTERNS FOR OUTSHELL ENERGY LEVEL
1A:
2A:
3A:
4A:
5A:
6A:
7A:
8A:
LEWIS DOT STRUCTURES (ELECTRON DOT)
H
C
O
Ne
PRACTICE
N
S
F
P
He
Ga
Si
Na