Quantum Numbers
The principal quantum number indicates the relative ______ of the orbital.
Size
At its top speed, a cheetah can spring the length of a football field (100.0 yards) in 2.73 seconds. What is its speed in kilometers per hour? Giver your answer to 3 sig figs.
1 yard = 3 ft 1 ft = 12 in 12 in = 2.54 cm
121 km/hr
In the photoelectric effect, what effect does increasing the intensity of light have on the experiment?
Increasing the intensity of light increases the number of electrons that are ejected per second
9345.1*0.45289+89.39
4321.7 (5 Sig Figs)
Which of the following are true?
A. The law of definite proportions applies to samples of two different compounds composed of the same elements
B. "Nitrogen dioxide always has a mass ration of 2.28 g O to 1 g N" Demonstrates the law of definite proportions
C. When 46g of a certain compound decomposes, it produces 14 g nitrogen and 32 g oxygen; the law of multiple proportions allows you to predict how much nitrogen and oxygen would be produced from the decomposition of a 156 g sample.
D. The law of multiple proportions applies to different samples of the same compound; for example, two different samples of C6H6O6
E. If 22 kg of gasoline reacts with 85 kg of oxygen gas, then the total mass of carbon dioxide and water vapor produced from the reaction must be 107kg; this demonstrates the law of conservation of mass.
F. The law of conservation of mass does not apply to combustion reactions, like burning a log in a campfire, because the mass of ashes remaining does not equal the mass of the log that was burned
B and E
The magnetic quantum number (m) describes the _____ of the orbital.
Orientation
Calculate the mass of 5.40E16 atoms of bismuth, Bi, in μg. Give your answer to 3 sig figs.
18.7 μg
The binding energy of electrons in a metal is 204 kJ/mol. Find the threshold frequency of the metal in Hz. Give your answer using 3 sig figs in scientific notation.
5.11E14 Hz
(9.95+0.05)/2.0000E3
0.005000 or 5.000E-3 (4 Sig Figs)
Gallium has two naturally occurring isotopes: Ga-69 (68.92558 amu) and Ga-71 (70.92470 amu). Find the mass of Ga-71 in a 4.500 g sample of naturally occurring gallium. Give your answer to 3 sig figs.
1.74 g
Which of the following are true?
A. Only 1 electron have a certain set of values for n, l, and ml in an atom
B. n designates the principle shell for an electron
C. The principle quantum number determines the size and energy of the orbitals; the angular momentum quantum number determines the shape of the orbital; the magnetic quantum number determines the orientation of the orbital.
D. Orbitals in the quantum mechanical model of the atom are very similar to orbits in the Bohr model of the atom
B and C
You would like to buy a window air conditioner to cool a room with an area of 29 m2. Window air conditioners are rated in BTU. It is recommended to get an air conditioner with a rating of 24 BTU/ft2 of the room's area. What BTU rating will you need for the air conditioner? Give your answer using 2 significant figures.
1ft = 12 in 1 in = 2.54 cm
7.5E3 BTU
When light with a wavelength of 363 nm strikes copper, the ejected electrons have 38.0 kJ/mol of kinetic energy. What is the threshold frequency for copper? Give your answer using 3 sig figs.
7.31E14 Hz
(4.50)/(1.5E3)+0.9970
1.0000 (5 Sig Figs)
Ar
What is wrong with the following quantum number designations?
n l m Name
1 1 0 1p
4 3 +1 4d
3 1 -2 3p
a) A sublevel with n = 1 can only have l = 0, not l =1. The correct sublevel name is 1s
(b) A sublevel with l = 3 is an f sublevel, not a d sublevel. The name should be 4f
c) A sublevel with l = 1 can have only -1, 0, or +1 for ml, not -2
Acetone has a density of 0.7857 g/cm3. How many liters of acetone are in 2.54E12 ng acetone? Give your answer to 3 sig figs.
1 cm3 = 1 mL
3.23 L
An electron has a mass of 9.109E-28 g and a deBroglie wavelength of 5.39 nm. Calculate its velocity in miles/hour. Give your answer using 3 sig figs.
1mile = 1.6093 km
3.02E5 mph
65.70/(0.755+3.145*2.19)
8.58 (3 Sig Figs)
______'s oil drop experiment determined the fundamental charge of the electron
Robert Millikan
Supply the missing quantum numbers and sublevel names.
n l m Name
? ? 0 4p
2 1 0 ?
? ? ? 2s
a) n = 4, l =1
b) 2p
c) n = 2, l = 0, m = 0
On account of the high heat and low humidity in the summer in Death Valley, a visitor requires about one quart of water for every two miles traveled on foot. Calculate the approximate number of liters required for a person to walk 18.0 kilometers in Death Valley. Give your answer in 3 sig figs.
1 mile = 5280 ft 1ft = 0.3048 m
1 gallon = 4 quarts 3.7854 L = 1 gallon
5.29 L
A laser pulse with a wavelength of 1.35 μm contains 2.15 mJ of energy. How many photons are in the laser pulse? (3 sig figs)
1.46E16 photons
((4.573*2.1) + (18.653-2.47)) / (3.05*(6.231+4.19))
0.811 (3 Sig Figs)
What's 2+2?
4