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WorksheetsAP Chemistry Unit 1
Total questions: 80
Worksheet time: 45mins
Which of the following numerical expressions gives the number of moles in 5.0g of CaO?
In a lab, a student is given a 21g sample of pure Cu metal. Which of the following pieces of information is most useful for determining the number of Cu atoms in the sample? Assume that the pressure and temperature in the lab are 1.0atm and 25°C.
The molar mass of Cu
The density of Cu at 25°C
The volume of the Cu sample
The ratio of the two main isotopes found in pure Cu
A 1.0mol sample of which of the following compounds has the greatest mass?
The mass spectrum for an unknown element is shown above. According to the information in the spectrum, the atomic mass of the unknown element is closest to
90 amu
91 amu
93 amu
94 amu
The mass spectrum represented above is most consistent with which of the following elements?
Eu
Gd
Tb
Dy
Based on the mass spectrum of a pure element represented above, the average atomic mass of the element is closest to which of the following?
185.7 amu
186.0 amu
186.3 amu
186.9 amu
A student obtains a 10.0g sample of a white powder labeled as BaCl2. After completely dissolving the powder in 50.0mL of distilled water, the student adds excess Na2SO4(s), which causes a precipitate of BaSO4(s) to form, as represented by the equation above. The student filters the BaSO4(s), rinses it, and dries it until its mass is constant. Which of the following scientific questions could best be answered based on the results of the experiment?
Is the Na2SO4(s) used in the experiment pure?
Is the BaCl2(s) used in the experiment pure?
What is the molar solubility of BaCl2 in water?
What is the molar solubility of BaSO4 in water?
A student measures the mass of a sample of a metallic element, M. Then the student heats the sample in air, where it completely reacts to form the compound MO. The student measures the mass of the compound that was formed. Which of the following questions can be answered from the results of the experiment?
What is the density of M?
What is the molar mass of M?
What is the melting point of M?
What is the melting point of MO?
A 42.0g sample of compound containing only C and H was analyzed. The results showed that the sample contained 36.0g of C and 6.0g of H. Which of the following questions about the compound can be answered using the results of the analysis?
What was the volume of the sample?
What is the molar mass of the compound?
What is the chemical stability of the compound?
What is the empirical formula of the compound?
A jar labeled NaCl contains a powder. The table above contains information determined by analyzing a sample of the powder in the laboratory. What information in the table is the most helpful in determining whether the powder is pure NaCl?
Mass
Mass percent of Na
Density
Color
A student obtains a mixture of the chlorides of two unknown metals, X and Z. The percent by mass of X and the percent by mass of Z in the mixture is known. Which of the following additional information is most helpful in calculating the mole percent of XCl(s) and of ZCl(s) in the mixture?
The number of isotopes of Cl
The molar masses of X and Z
The density of either XCl(s) or ZCl(s)
The percent by mass of Cl in the mixture
A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known. Which of the following information is needed to determine the mole fraction of each gas in the mixture?
The molar mass of each gas
The density of the gases in the vessel
The total pressure of the gases in the vessel
The number of atoms per molecule for each gas
How many unpaired electrons are in the atom represented by the electron configuration above?
0
1
2
3
Which of the following represents the electron configuration of an oxygen atom in the ground state?
Which of the following is the correct electron configuration for a ground-state atom of magnesium (atomic number 12) ?
The complete photoelectron spectrum of an element is given above. Which labeled peak corresponds to the 1s electrons and why?
Peak X, because 1s electrons are the easiest to remove from the atom.
Peak X, because 1s electrons have the strongest attractions to the nucleus.
Peak Y, because electrons in the 1s sublevel are the farthest from the nucleus.
Peak Y, because there are fewer electrons in an s sublevel than in a p sublevel.
The photoelectron spectrum for the element boron is represented above. Which of the following best explains how the spectrum is consistent with the electron shell model of the atom?
The spectrum shows an odd number electrons.
The spectrum shows a single electron in the 2p subshell.
The spectrum shows equal numbers of electrons in the first and second electron shells.
The spectrum shows three electrons with the same binding energy in the second electron shell.
The complete photoelectron spectrum of the element carbon is represented above. Which of the following best explains how the spectrum is consistent with the electron shell model of the atom?
The spectrum shows four electrons in the inner electron shell.
The spectrum shows equal numbers of electrons in the three occupied electron subshells.
The spectrum shows that all the electrons in the valence shell have the same binding energy.
The spectrum shows more electrons in the inner electron shell than in the outer electron shell.
The atomic radii of the elements in the nitrogen group in the periodic table are given in the table above. Which of the following best helps explain the trend of increasing atomic radius from N to Bi?
The number of particles in the nucleus of the atom increases.
The number of electrons in the outermost shell of the atom increases.
The attractive force between the valence electrons and the nuclei of the atoms decreases.
The repulsive force between the valence electrons and the electrons in the inner shells decreases.
Which of the following best helps to explain why the atomic radius of K is greater than that of Br?
The first ionization energy of K is higher than that of Br.
The valence electrons in K are in a higher principal energy level than those of Br.
In the ground state, an atom of K has fewer unpaired electrons than an atom of Br has.
The effective nuclear charge experienced by valence electrons is smaller for K than for Br.
Which of the following best helps explain why the first ionization energy of K is less than that of Ca?
The electronegativity of K is greater than that of Ca.
The atomic radius of the K atom is less than that of the Ca atom.
The valence electron of K experiences a lower effective nuclear charge than the valence electrons of Ca.
The nucleus of the K atom has fewer neutrons, on average, than the nucleus of the Ca atom has.
Which of the following best helps explain why an atom of Rb gas more easily loses an electron in a chemical reaction than an atom of Li gas?
Rb has a higher electronegativity than Li has.
The Rb atom has a greater number of valence electrons than the Li atom has.
The nucleus of the Rb atom has a greater number of protons and neutrons than the nucleus of the Li atom has.
In the Rb atom the valence electron is farther from its nucleus than the valence electron of Li is from its nucleus.
Rb reacts with O in a mole ratio of 2 to 1, forming the ionic compound Rb2O. Which of the following elements will react with O in a mole ratio of 2 to 1, forming an ionic compound, and why?
S, because it is in the same group as O.
Cs, because it is in the same group as Rb.
Sr, because it is in the same period as Rb.
Br, because the atomic mass of Br is similar to that of Rb.
What charge does Al typically have in ionic compounds, and why?
+1, because in the ground state it has one unpaired electron.
+2, because it has two electrons in the 2s subshell.
+3, because it has three valence electrons.
+4, because it is in the fourth row of the periodic table.
A student obtains a sample of a pure solid compound. In addition to Avogadro's number, which of the following must the student know in order to determine how many molecules are in the sample.
molar mass of the compound and density of the sample
mass of the sample and the volume of the sample
molar mass of the compound and mass of the sample
mass of the sample and density of the sample
Which of the following would be the correct formula for calculating the percent water in lithium sulfate trihydate?
54/ 163.9 x 100
20.7/163.9 x 100
36/163.9 x 100
18/163.9 x 100
A student has a 1 g sample of each of the following compounds: NaCl, KBr, and KCl. Which of the following lists the samples in order of increasing number of moles in the sample.
NaCl < KCl < KBr
KCl < NaCl < KBr
NaCl < KBr < KCl
KBr < KCl < NaCl
The mass spectrum of the element Sb is most likely represented by which of the following?
The natural occurring isotopes of boron are 10B and 11 Given that the average atomic mass of boron is 10.811 then the % abundance of boron -11 is closest to
10%
50%
20%
80%
How many carbon atoms are contained in 2.8 g of C2H4?
1.2 x 1024
3.0 x 1023
1.2 x 1023
6.0 x 1024
6.0 x 1023
Which of the following statements are TRUE?
1, 2, 4
3, 4
3 only
2, 3, 4
1, 2, 3
When a hydrogen electron makes a transition from n = 3 to n =1, which of the following statements are true?
1, 4
5
2, 4
1, 3
2, 3
Which of the following frequencies corresponds to light with the longest wavelength?
9.12 x 1012 Hz
3.20 x 109 Hz
4.12 x 105 Hz
3.00 x 1013 Hz
8.50 x 1020 Hz
A sample containing atoms of C and F was analyzed using x-ray photoelectron spectroscopy. The portion of the spectrum showing the 1s peaks for atoms of the two elements is shown below. Which of the following correctly identifies the 1s peak for the F atoms and provided an appropriate explanation?
Peak Y, because F is more electronegative than C is
Peak X, because F has a greater nuclear charge than C has
Peak Y, because F has a smaller atomic radius than C has
Peak X, because F has a smaller ionization energy than C has
Identify the element represented by the PES shown below.
Na
K
Ar
Ca
Below is a PES for two elements; X (pink) and Y (Blue). What is the electron configuration for element X?
1s22s22p63s23p1
1s22s22p63s23p64s2
1s22s22p63s23p6
1s22s22p63s2
Which set of orbital diagrams shows a violation of Hund’s Rule for an atom in its ground state.
1
2
3
4
Which sketch may represent an orbital with the quantum numbers n= 3, l = 2 ?
4 and 5
2 and 3
2, 3, 5
5
What quantum numbers must be the same for orbitals to be degenerate (equal energy)?
1 and 2
1
1, 2, and 3
all 4 quantum numbers
Which of the following atoms or ions has three unpaired electrons?
Al
S2-
N
Ti2+
O
Which of the following is NOT directly determined by the principal quantum number, n, of the electron in an atom?
the energy of the electron
the shape of the corresponding atomic orbital(s)
the size of the corresponding atomic orbital(s)
the distance of the electron from the nucleus
How many total electrons in an atom can have the quantum numbers n =4, l = 2, ml = –1 ?
6
10
2
18
5
Which set of quantum numbers cannot be correct:
n = 2, l = 1, ml = –1
n = 3, l = 1, ml = –1
n = 1, l = 1, ml = 1
n = 2, l = 0, ml = 0
Which of the following statements is FALSE?
The 3s orbital is held more tightly by the nucleus than the 2s orbital.
The spin quantum number of an electron must be either +½ or –½ .
In the usual order of filling, the 7s orbital is filled before the 5f orbital
An orbital can accommodate at most two electrons.
Which of the following represents the electron configuration for the C-4 ion
1s2 2s2 2p2
1s2 2s2 2p4
1s2
1s2 2s2 2p6
Based in on the ionization energies of element X given in the table below, which of the following is most likely the empirical formula of an oxide of element X
XO2
X2O3
X2O5
X2O
Based on periodic trend and the data in the table below, which of the following are the mot probably values of the atomic radius and the first ionization energy for lithium and beryllium.
210 pm, 463 kJ/mol
112 pm, 890 kJ/mol
112 pm, 463 kJ/mol
210 pm, 890 kJ/mol
The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. The difference best accounts for which of the following?
Na has a greater density at standard condition than Ne
Na has a lower first ionization energy than Ne
Na has a higher neutron to proton ratio than Ne
Na has a higher melting point that Ne
Why doesn’t sodium ordinarily occur in the +2 ion state?
large atomic radius
high 2nd ionization energy
low electron affinity
small density
high first ionization energy
Examine the following graph. What formula would result if element D formed a compound with phosphide
D3P4
D3P2
D3P
DP
Strontium’s ionization energy is less than beryllium’s. This is accounted for because
strontium has more energy levels that beryllium
beryllium has a greater nuclear charge than strontium
strontium has a stronger Coulombic attraction than beryllium
strontium has more protons than beryllium
Examine the following isoelectronic series.
K1+, P3-, S2- , Cl1-
You would expect
P3- to be the largest because it has the least electrons
P3- to be the largest because it has the most electrons
P3- to be the largest because it has the least protons
P3- to be the smallest because it has the most protons
Rank the following atoms or ions in order of increasing radius: Al+3, Mg+2, O-2, N-3?
none of these
Al+3, Mg+2, O-2, N-3
N-3, O-2, Mg+2, Al+3
O-2, N-3, Al+3, Mg+2
Mg+2, Al+3 , N-3, O-2
Which of the following represent an isoelectronic series?
4, 5, 6
1, 2, 5, 6
1, 2, 3, 5
1 and 2
If element C is a member of the 3rd period, what element is it?
Al
Si
Mg
P
How many valence electrons does element D have?
1
3
4
5
If element B were to form a compound with oxide, what would the formula be
BO
B2O3
B2O
BO2
Which of the four element would you expect to have the smallest atomic radius?
A
B
C
D
Identify the element represented in spectrum 2
Na
Mg
Al
Li
How many valence electrons does the element in spectrum 3 have?
2
8
3
6
If the element in spectrum 1 forms an ionic compound with nitride, what would you expect the formula to be? Use X to represent the element in spectrum 1
(a)
Look at the element in spectrum 2 and spectrum 3. The 1s electrons in spectrum 3 have a higher binding energy (the 1s peak is to the left indicating that the electrons are held tighter to the nucleus) than the 1s electrons in spectrum 2. What is different about the element in spectrum
(a)
In the following PES, which peak represents the 3s electrons?
37.1 MJ/mol
347 MJ/mol
0.42 MJ/mol
3.93 MJ/mol
Determine the identity of the element in the PES below. If the PES of Calcium were placed on top of the PES below, where would you expect the peak for Ca's 1s electrons to be?
Between the 5.31 MJ/mol and 0.74 MJ/mol peaks
To the right of the 126 MJ/mol peak
To the left of the 126 MJ/mol peak
To the right of the 0.74 MJ/mol peak
What is the symbol for the element represented in the photoelectron spectrum below?
(a)
What is the symbol of the element represented in the following photo electrons spectrum?
(a)
What the electron configuration for the element in the following PES
1s2 2s2 2p6 3s2 3p6 4s1
1s2 2s2 2p6 3s2 3p3
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p1
What electron is represented by 5,1, 1,1/2
(a)
Which electron is represented by 7,1,1,-1/2
(a)
Which element's electron configuration ends with 3d2
(a)
What are the quantum numbers for the last electron in Sn
(a)
What is the noble gas configuration for W?
(a)
An photon has a wavelength 1.6 x 10-8 m. Determine the frequency of the wave.
1.8 x 1016 1/s
3.3 x 10-17 1/s
4.8 1/s
1.6 x 10 -8 1/s
An photon has a wavelength 1.6 x 10-8 m. Determine the energy of the photon.
1.2 x 10 -17 J
4.1 x 10 -26 J
1.1 x 10 -41 J
3.7 x 10 -9 J
It is determined that a photon with an energy of 3.2 x 10 -21 J is needed for an electron transition. What is the quantity of energy for electron transitions in a mole of the element.
312 kJ/mol
1.9 kJ/mol
1.1 kJ/mol
153 kJ/mol
In order for an electron to transition from n= 4 to n= 7 in an atom, energy is __________ and the process is ______.
absorbed , endothermic
absorbed, exothermic
emitted, exothermic
emitted, endothermic
The energy involved for an electron to transition from n =1 to n=6 is ____________ the energy involved for an electron to transition from n=6 to n=1
equal
more than
less than
cannot be determined
In a hydrogen atom the energy involved for an electron to transition from n =1 to n=3 is ____________ the energy involved for an electron to transition from n=3 to n=6
equal to
larger than
less than
cannot be determined
In a hydrogen atom an electron transitions from n = 3 to n = 7. Determine the energy of the photon involved in this process and state if it is exothermic or exothermic
1.98 x 10 -19 J, endothermic
1.98 x 10 -19 J , exothermic
6.0 x 10 -34 J endothermic
6.0 x 10 -34 J exothermic
Potassium has an ionization energy of 431 kJ/mol. Determine the energy of a photon needed to eject one electron from one potassium ion. And determine the wavelength, in nm, of this photon
7.2 x 10 -19 J, 278 nm
7.2 x 10 -19 J, 2.8 x 10 -7 nm
7.16 x 10 -22 J, 2.8 x 10 -4 nm
7.16 x 10 -22 J, 278000 nm
