|
PS 1422
Lecture Note Chaps 6 & 7: Sound Waves and Atomic Structure Wave Motion and Sound: The origin of any wave is a vibration and the wave
is the disturbance through the medium. The number of wave troughs or crests passing a given point per second is called frequency. Light waves can be transmitted through the vacuum but sound wave cannot travel through
vacuum. The wave velocity is simply the product of frequency and the wavelength. What happens to the wavelength if the frequency is doubled or vice versa? An oscillating tuning fork causes an identical fork to oscillate
this is called resonance. What is Doppler effect, when a source of sound approaches or recedes the observer? On this basis explain red shift and blue shift of the stars. The quality of sound is determined by the
presence of the overtones. Without the harmonics or overtones the sound would be uninteresting. A traveling wave train has a wavelength of 0.50 m and a speed of 20 m/s. Then the wave frequency is 40 Hz. A musical tone
sounded on a piano has a frequency of 410 Hz and wavelength in air of 0.80 m. Then the wave speed would be 328 m/s. If the Ocean waves with a wavelength of 120 m are coming in at a rate of 8 per minute. What is their
speed? The trough of a sine wave that is used to represent a sound wave corresponds to a rarefaction. What beat frequency will two tuning forks held side by side create if their frequencies are 342 Hz and 345
Hz? What is the lowest frequency that will resonate in a 2-m long organ pipe that is closed at one end if the speed of sound in air is 340 m/s? If a guitar string has a fundamental frequency of 500 Hz, what is the
frequency of its 11th overtone? For a standing wave in an air column in a pipe that is open at both ends, there must be at least two antinodes and one node. How far away is a lightening strike if you hear the
thunderclap 3s after you see the lightening bolt strike? V (sound) = 340 m/s. The amplitude corresponds to the loudness of the sound. An airplane will generate a shock wave if it is traveling at twice the speed of sound
and sonar range detecting is based on reflection. Atomic Structure and Periodic Table: The place of an element in the periodic table is found by its atomic number. An element is a collection of atoms with
identical nuclear charges. Orbitals which are designated s, p, d, f,.. are those for which l=0, l=1, l=2, l=3,... respectively. The ground state electron configuration for Na (Z = 11) is 1s22s2 2p
6 3s1. What is the ground state electron configuration for silicon? It was Pauli who proposed the principle that no more than one electron may occupy a given quantum state. The atomic mass of an
element is equal to the sum of protons and neutrons in the nucleus. The number of neutrons is equal to the difference of mass number and the atomic number, which is A-Z. The concept of quantum mechanics is based on the
fact that energy is quantized. What is an atomic orbit? Well it is a region in space where an electron quite likely can be found. The most important factor in the determination of the chemical activity of an atom is its
electron configuration. The dumbbell-shaped p orbitals first appear when principle quantum number is n=2. The maximum number of electrons the 5d atomic orbitals can hold is 10. Some sample problems:
A sound wave with a speed of 334 m/s and a wavelength of 3.0 m has a frequency of a. 1000 Hz c. 111 Hz
b. 337 Hz d. 1/111 Hz What beat frequency will two vibrating tuning forks held side by side
create if their frequencies are 343 Hz and 345 Hz? a. 687 Hz c. 339 Hz
b. 343.5 Hz d. 2 Hz What is the lowest frequency that will resonate in a 2-m long organ pipe that is closed
at one end if the speed of sound in air is 340 m/s? a. 42.5 Hz c. 170 Hz
b. 85 Hz d. 680 Hz
If a guitar string has a fundamental frequency of 500 Hz, what is the frequency of its second overtone?
a. 250 Hz c. 1000 Hz
b. 750 Hz d. 1500 Hz Amplitude corresponds to
a. frequency c. loudness
b. noise d. velocity A bow wave is produced when a boat moves
a. slower than the velocity of waves in water b. as fast as the waves in water c. faster than the velocity of waves in water d. at any speed An atom is said to be excited when one or more
a. electrons are removed b. electrons are in higher energy levels than normal c. protons are removed d. protons are in higher energy levels than normal For a given l quantum number, the ml
quantum number can have how many values? a. n2 b. 1/2l c. 2l + 1 d. 2(l +1) The place of an element in the periodic table is determined by its
a. mass number c. atomic number
b. density d. atomic mass An element is a collection of atoms with a. identical numbers of neutrons
b. identical nuclear masses c. identical nuclear charges d. all of these Orbital which are designated p are those for which a. l
=3 c. m=1
b. n=2 d. l =1
The ground state electron configuration for silicon (Z=14) is a. 1s22s22p62d4 b. 1s2
1p62s22p4 c. 1s22s22p43s23p4
d. 1s22s22p63s23p2 What is the total electron capacity of the energy level for which n=4?
a. 8 c. 18
b. 16 d. 32
The principle that no more than one electron may occupy a given quantum state in an atom was first stated by
a. Bohr c. Heisenberg
b. de Broglie d. Pauli The atomic number of an element is equivalent to a. the proton number in the nucleus
b. the neutron number in the nucleus c. the sum of protons and neutrons d. the number of electrons in the outer shells If A is the mass number and Z is the atomic number, the A-Z is a. a negative number
b. the number of protons c. the number of electrons d. the number of neutrons An atomic orbital is a. a region in space where it is quite likely that an electron can be found
b. a region in space where an electron spends all of its time c. a region in space surrounding a nucleus where an electron is not likely to be found d. the path in space taken by an electron
For a d subshell, the total number of ml values is
a. 2 c. 4
b. 3 d. 5 The notation "4d" means a. n=3,l
=4 c. n=4, m=3 b. n=4,l
=2 d. n=4, l=5 The dumbbell-shaped p orbitals first appear when
a. n=1 c. n=3
b. n=2 d. l=0 The orbital that has the lowest energy is
a. p c. s
b. f d. d If an atom emits a photon
a. an electron leaves the atom b. an electron is promoted to a higher energy level c. an electron drops to a lower energy level d. the electrons are unaffected The Bohr theory of the atom
a. assumed that electrons could revolve around the nucleus in any orbits b. wasn't consistent with Rutherford's model c. didn't consider that electrons exhibit wave behavior
d. didn't consider that electrons and photons are identical The origin of any wave motion is:
a. a condensation c. velocity b. a vibration d. wavelength
The number of wave crests passing a given point per second is called a. frequency c. wavelength
b. velocity d. amplitude As the temperature of air increases, the velocity of sound waves in air
a. remains constant c. decreases
b. increases d. may increase or decrease If the frequency of a sound is doubled, the wavelength is
a. not affected b. doubled c. halved d. 4 times the original wavelength A vibrating tuning fork causes an identical fork nearby to vibrate. This is called
a. reverberation c. beats b. refraction d. resonance
When a source of sound approaches, measurements will show an increase in the sound's a. wavelength c. frequency
b. speed d. all of these The quality of a sound is determined by
a. the loudness of the sound b. the pitch c. the presence of overtones d. beats A traveling wave train has a wavelength of 1.0 m and a speed of 20 m/s. What is the wave frequency?
a. 0.025 Hz c. 40 Hz
b. 20 Hz d. 10 Hz A musical tone sounded on a piano has a frequency of 410 Hz and a
wavelength in air of 0.80 m. What is the wave speed? a. 170 m/s c. 328 m/s
b. 235 m/s d. 587 m/s
Ocean waves with a wavelength of 180 m are coming in at a rate of 8 per minute. What is their speed?
a. 8 m/s c. 24 m/s
b. 16 m/s d. 30 m/s The trough of a sine wave that is used to represent a sound wave corresponds to a
a. rarefaction b. condensation c. point where molecules oscillate at a right angle to the direction of wave travel d. wavelength 
|
