01:160:159 Lecture 7: chap07notes
AP Chemistry
A. Allan
Chapter 7 Notes - Atomic Structure and Periodicity
7.1 Electromagnetic Radiation
A. Types of EM Radiation (wavelengths in meters)
10-12
10-10
10-8
4 to 7x10-7
10-4
10-2 1
102
104
gamma
xrays
UV
visible
IR
micro
Radio waves
FM short AM
Wavelength increases
Frequency decreases
Energy decreases
Speed is constant = 2.9979 x 108 m/sec
B. Properties of EM Waves
1. Wavelength ()
a. Distance between two consecutive peaks or troughs in a wave
b. Measured in meters (SI system)
2. Frequency ()
a. Number of waves that pass a given point per second
b. Measured in hertz (sec-1)
3. Speed ( c )
a. Measured in meters/sec
4. Relationship of properties
a.
= c
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7.2 The Nature of Matter
A. Max Planck and Quantum Theory
1. Energy is gained or lost in whole number multiples of the quantity
hv Frequency = v
Planck's constant =h = 6.626 x 10-34 J•S
E = nhv
2. Energy is transferred to matter in packets of energy, each called
a quantum
B. Einstein and the Particle Nature of Matter
1. EM radiation is a stream of particles - "photons"
hc
E photon = hv =
2. Energy and mass are inter-related
E = mc2
C. de Broglie and the Dual Nature of Light
1. Light travels through space as a wave
2. Light transmits energy as a particle
3. Particle's have wavelength, exhibited by diffraction patterns
=
h
mv
a. large particles have very short wavelengths
b. All matter exhibits both particle and wave properties
7.3 The Atomic Spectrum of Hydrogen
A. Continuous spectra
1. Contains all wavelengths of light
B. Bright line spectra
410nm 434nm 486nm 656nm
1. Excited electrons in an atom return to lower energy states
2. Energy is emitted in the form of a photon of definite wavelength
3. Definite change in energy corresponds to:
a. Definite frequency
b. Definite wavelength
hc
E = hv =
4. Only certain energies are possible within any atom
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7.4 Bohr Model (Neils Bohr, 1913)
A. Quantum Model
1. The electron moves around the nucleus only in certain allowed circular
orbits
2. Bright line spectra confirms that only certain energies exist in the atom,
and atom emits photons with definite wavelengths when the electron
returns to a lower energy state
3. Energy levels available to the electron in the hydrogen atom
æ
Z
2
ö
−18
ç
÷
E = - 2.178 x10
J ç
÷
2
è
n
ø
n = an integer Z = nuclear charge
J = energy in joules
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Document Summary
Chapter 7 notes - atomic structure and periodicity. 7. 1 electromagnetic radiation: types of em radiation (wavelengths in meters) 7. 2 the nature of matter: max planck and quantum theory, energy is gained or lost in whole number multiples of the quantity hv frequency = v. Planck"s constant =h = 6. 626 x 10-34 j s. E nhv: energy is transferred to matter in packets of energy, each called a quantum, einstein and the particle nature of matter, em radiation is a stream of particles - photons hc hv. E photon: energy and mass are inter-related. E = mc2: de broglie and the dual nature of light, light travels through space as a wave, light transmits energy as a particle, particle"s have wavelength, exhibited by diffraction patterns. = h mv: large particles have very short wavelengths, all matter exhibits both particle and wave properties. 7. 3 the atomic spectrum of hydrogen: continuous spectra, contains all wavelengths of light, bright line spectra.
