AP CHEM MIDTERM (UNITS 1 AND 2)
Which of the following atoms would form a solid metal with the highest melting point?
- diagram with the most orbitals/layers
Which species is planar? a. cos3^2- b. SO3^2- c. CIO3- d. BF4-
A. cos3^2-
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? a. Mass of the sample, volume of the sample b. Mass of the sample, density of the sample c. Molar mass of the compound, mass of the sample d. Molar mass of the compound, density of the sample
C. Molar mass of the compound, mass of the sample
Of the following compounds, which is the most ionic? a. SiCl b. BrCI c. PCIs D. CaCl2
D. CaCl2
On the basis of the information opposite, which of the following arranges the binary compounds in order of increasing bond polarity? a CH4 < SiC4, < SF4 B. CHA< SF4 < SiCl4 c. SF4< CH4 < SiCl4 d SiCl4< SF4 < CH4
a CH4 < SiC4, < SF4
Which of the following has the bonds arranged in order of decreasing polarity? a H-F> N-F> F-F B. Н-І > Н-Вг > H-F c. O-N> O-S > 0-Te d. Sb-| > Sb-Te > Sb-CI
a H-F> N-F> F-F
Peaks A, B, and C represent the binding energies of electrons in which subshells of neon? a. 1s, 2s, 2p b. 2p, 2s, 1s c. 1s, 1s, 1s d. 2s, 2p, 2p
a. 1s, 2s, 2p
Which of the following represents the ground state electron configuration for the Mn3+ ion? a. 1s22s22p63s23p63d4 b. 1s22s22p63s23p63d54s2 c. 1s22s22p63s23p63d24s2 d. 1s22s22p63s23p63d84s2 e. 1s22s22p63s23p63d34s1
a. 1s22s22p63s23p63d4
How many protons, neutrons, and electrons are in an 56Fe atom? Protons Neutrons Electrons a. 26 30 26 b. 26 56 26 c. 30 26 30 d. 56 26 26
a. 26 30 26
Consider the table below showing the melting and boiling points of three of the alkali metals, along with their specific gravities. Which of the following statements offers the best explanation of the data in the table concerning the observed trends, going from solution to potassium to rubidium? a. As the metal atoms increase in size, they get farther apart from each other, so their melting and boiling points decrease. The strength of dispersion forcesamong neutral atoms decreases with increasing distance between atoms. b. The valence electrons get farther and farther apart from the nucleus as the atomic number increases, weakening the pull of the nucleus on the valence level. c. The valence electrons in the metallic lattice are farther from the nuclei. so they do not bind the atoms as tightly to each other. As a result, less thermal energy is needed to disrupt the solid lattice or to overcome the attractive force
a. As the metal atoms increase in size, they get farther apart from each other, so their melting and boiling points decrease. The strength of dispersion forcesamong neutral atoms decreases with increasing distance between atoms.
Which of the following alkali metals would have the strongest Coulombic forces, leading to the highest melting point when paired with the corresponding halogen in the same period a. Li b. Na c. K d. Rb
a. Li
Which of the following best explains why metals are good conductors of electricity? a. Metallic bonding can be described as an "electron sea" with mobile valence electrons. b. Metals tend to have higher densities than nonmetals c. Metal tend to have higher melting points than nonmetals. d. Metals tend to have rather large values for electronegativity.
a. Metallic bonding can be described as an "electron sea" with mobile valence electrons.
A sample of nitrogen and oxygen-containing molecules is decomposed into its elements. It is found to contain 14.0 g of nitrogen and 40.0 of oxygen. Which of the following is the empirical formula of the compound? a. N2O5 b. NOs c. NOz d. N206
a. N2O5
A student has a 1.0 g sample of each of the following compounds: NaCI, KBr, and KCL Which of the following lists the samples in order of increasing number of moles in the sample? a. NaCI < KCI < KBr b. NaCI < KBr < KCI c. KCI < NaCI < KBr d. KBr < KCI < NaCI
a. NaCI < KCI < KBr
Based on the data in the tables opposite, which of the following statements provides the best prediction for the boiling point of NaCI? a. NaCI will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCi than in NaF. b. NaCI will have a boiling point between that of NaF and Mo because te covalen characier on the bonds in was is intermediate between that of MgO and NaF. c. NaCI will have a higher boiling point than MO because the ions are spaced farther apart in NaCi. d. NaCI will have a higher boiling point than MO because the eneroy requireo to transter electons from the anion to the cation is larger in NaCI than in MgO.
a. NaCI will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCi than in NaF.
Which of the following arranges the atoms and ions in order of increasing radius? a. Rb+ < Kr < Br- b. Br- < Kr < Rb+ c. Kr < Br- < Rb+ d. Kr < Rb+ < Br-
a. Rb+ < Kr < Br-
The atom that contains exactly two unpaired electrons a. S b. Ca c. Ga d. Sb e. Br
a. S
Based on Coulombic forces, which of the following will have the highest melting point? a. Sodium b. Magnesium c. Zinc d. Aluminum
a. Sodium
The potential energy of a system of two atoms as a function a function of their internuclear distance is shown in the diagram opposite. Which of the following is true regarding the forces between the atoms when their internuclear distance is X? a. The attractive and repulsive forces are balanced, so the atoms atoms will maintain an average internuclear distance x. b. There is a net repulsive force pushing the atoms apart, so the atoms will move further apart c. There is a net attractive force pulling the atoms together, so the atoms will move closer together. d. It cannot be determined whether the forces between atoms are balanced, attractive, or repulsive, because the diagram shows only the potential energy.
a. The attractive and repulsive forces are balanced, so the atoms atoms will maintain an average internuclear distance x.
What differentiates a homogeneous mixture from a pure substance? a. The composition of a pure substance is fixed b. A pure substance can be separated into elements by physical means c. A pure substance is always a compound while mixtures can be elements or compounds d. A homogeneous mixture is uniform throughout
a. The composition of a pure substance is fixed
Metals are typically shiny and electrically conductive, while ionic solids are dull and electrically insulating. Which feature of metals is responsible for this difference? a. The delocalized electrons b. The number of neutrons in the nuclei c. The charges of the positive ions d. The crystal lattice of positive ions
a. The delocalized electrons
Which of the following statements best describes the first ionization energies of sodium compared to potassium? a. The first ionization of sodium is greater than for potassium due to a lower effective nuclear charge. b. The first ionization energy for sodium is less than for potassium due to a greater effective nuclear charge. c. The first ionization energy for sodium is greater than for potassium due to lower nuclear shielding. d. The first ionization energy for sodium is less than for potassium due to greater nuclear shielding.
a. The first ionization of sodium is greater than for potassium due to a lower effective nuclear charge.
The mass percent of carbon in pure glucose, C6H1206, is 40.0 %. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2%. Which of the following impurities could account for the low mass percent of carbon in the sample? a. Water, H20 b. Fructose, C6H1206, isomer of glucose c. Ribose, C5H1005 d. Sucrose, C12H22011
a. Water, H20
A student has samples of two pure compounds, XCIO3 and ZCIO3., which contain unknown alkali metal. X and Z. The student measures the mass of each sample and then strongly heats the samples to drive off all the oxygen, leaving solid residues of XCI and ZCI. The student measures the mass of the solid residue from each sample. Which of the following questions can be answered from the results of the experiment? a. Which has the greater molar mass, X or Z? b. Which has the higher boiling point, X or Z? c. Which has the higher melting point, XCI or ZCI? d. Which has the greater density, XCI or ZCI?
a. Which has the greater molar mass, X or Z?
Which of the following statements best accounts for peak C being three times the height of peak B: a. the intensity of the photoelectron signal at a given energy is a measure of the number of electrons in that energy level. b. electrons represented by peak B have approximately triple the binding energy than those represented by peak C. c. in a photoelectron spectrum, as binding energy increases the relative number of electrons decreases. d. the height of peaks in a photoelectron spectrum does not have any relation to the structure of the atom
a. the intensity of the photoelectron signal at a given energy is a measure of the number of electrons in that energy level.
A solution is prepared by adding 16.0 g of CH OH to 90.0 g of H2O. The mole fraction of CH OH in this solution is closest to which of the following? a, 0.1 b. 0.2 c. 0.3 d 0.4
b. 0.2
Of the following electron contigurations ot neutral atoms, which represents an atom in an excited state? a. 1s22s22p5 b. 1s22s22p53s2 c. 1s22s22p53s1 d. 1s22s22p53s23p2 e. 1s22s22p53s22p5
b. 1s22s22p53s2
A 34.1 q sample of a copper(Il) chloride hydrate was heated to drive off the water. The remaining anhydrous sample was 26.9 g. Which of the following is the number of waters of hydration in the hydrate? a. 6 b. 2 c. 9 d. 3
b. 2
Nitrogen shows 3 peaks in its photoelectron spectrum. These 3 peaks correspond to the binding energies of nitrogen's 1s, 2s and 2p electrons. The relative heights of the 1s, 2s, and 2p peaks in the PES spectrum of nitrogen will be: a. 1, 1, 1 b. 2, 2, 3 c. 1, 1, 2 d. 2, 2, 5
b. 2, 2, 3
Which of the following ionic compounds is likely to have the highest melting point? a. NaCI b. AIN c. MgS d. K2S
b. AIN
Which of the following elements is represented by the graph at right? vate: a. Br b. B c. Na d. Ne
b. B
The first five ionization energies of a second-period element are listed in the table at right. Which of the following correctly identifies the element and best explains the data? a. B, because it has five core electrons b. B. because it has three valence electrons c. N, because it has five valence electrons d. N, because it has three electrons in the p sublevel
b. B. because it has three valence electrons
Which of the following elements would be BEST to mix with Fe in the formation of an interstitial alloy, if Fe has an atomic radius of 156 pm? a. Sn: 145 pm b. C: 67 pm c. Zn: 142 pm d. Ni: 149 pm
b. C: 67 pm
Which of the following has the greatest percent by mass of carbon? a. HCN b. CH4 c. CO2 d. CO
b. CH4
Which of the following identifies the element and provides the best explanation? a. Carbon, because it has four valence electrons. b. Carbon, because it has four valence electrons. c. Oxygen, because it has six valence electrons. d. Oxygen, because it has four electrons in its 2p sublevel.
b. Carbon, because it has four valence electrons.
Which pair of atoms has the most polar bond? a. H-Br b. H-CI c. H-I d. I-CI
b. H-CI
Which of the following ranks the following elements (Si, N, In, Ne) in order of increasing first ionization energy? a. In < Si < Ne < N b. In < Si < N < Ne c. In < N < Si < Ne d. Ne < N < In < Si
b. In < Si < N < Ne
2. The mass spectrum of a sample of a pure element is shown at right. Based on the data, the peak at 26 amu represents an isotope of which of the following elements/ a. Al with 13 neutrons b. Mg with 14 neutrons c. Fe with ze neutrons d. Ti with 26 neutrons
b. Mg with 14 neutrons
According to the information in the table at right, a 1.00 g sample of which of the following contains the greatest mass of oxygen? a. Na.O b. MgO c. K20 d. CaO
b. MgO
Which of the following elements has the mass spectrum represented at right? a Nb b. Mo c. U d. Cf
b. Mo
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. This difference best accounts for which of the following? a. Na has a greater density at standard conditions than Ne. b. Na has a lower first ionization energy than Ne. c. Na has a higher melting point than Ne d. Na has a higher neutron-to-proton ratio than Ne. e. Na has fewer naturally occurring isotopes than Ne.
b. Na has a lower first ionization energy than Ne.
Which of the following is the best description of electrical conduction in a solid metal? a. Positive ions flow through a lattice of negative ions. b. Negatively charged elementary particles flow through a lattice of positive ions c. Positively charged elementary particles flow through a lattice of positive ions. d. Positively charged elementary particles flow through a lattice of negative ions e. Negative ions flow through a lattice of positive ions.
b. Negatively charged elementary particles flow through a lattice of positive ions
Which species has exactlv five pairs of electrons around the central atom? a. CIF5 b. SF4 c. SF5- d. XeF4
b. SF4
The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true? a. The carbon-to-selenium bond is unstable. b. The carbon-to-selenium bond is nonpolar covalent. c. The compound has the empirical formula CSe. d. A molecule of the compound will have a partial negative charge on the carbon atom.
b. The carbon-to-selenium bond is nonpolar covalent.
After completing an experiment to determine gravimetrically the percentage(of water in a frydrate, a student reported a value of 38%. The correct value for the percentage of water in the hydrate is 51%. Which of the following is the most likely explanation for this difference? a. Strong initial heating caused some of the hydrate sampte to spatter out of the crucible. b. The dehydrated sample absorbed moisture after heating c. The amount of the hydrate sample used was too small. The crucible was not heatedto constant mass before use e. Excess heating caused the dehydrated sample to decompose.
b. The dehydrated sample absorbed moisture after heating
A student is given two 10 g samples, each a mixture of only NaC(sand Cs) but in different proportions. Which of the following pieces of information could be used to determine which mixture has the higher proportion of KCI(s)? a. The volume o each mixure b. The mass of Cl in each mixture c. The number of isotopes of Na and K d. The reaction or each mixture with water
b. The mass of Cl in each mixture
Which of the following can be inferred from the diagram opposite that shows the dependence of potential energy on the internuclear distance between two atoms? a. The atoms form a bond with a bond length of 25 pm. b. The net force beiween the aiomsis alracive a 25 pm. c. The atoms form a bond with a bond length of 75 pm. d. The net force between the atoms is attractive at 75 pm.
b. The net force beiween the aiomsis alracive a 25 pm.
Als) is a relatively malleable metal. When Als) forms an alloy with Cu(s), however, it becomes less malleable. Which of the following explanations accounts for this observation? a. The larger mass of Cu(s) causes the density to increase, and more force is required to manipulate the greater mass b. The relatively different radi of the metals result in the atoms being in a more disordered arrangement, so the atoms are unable to slide past one another as easily. c. Since the atoms have different electron configurations, the electrons are unable to flow from atom to atom in the valence shells. d. The covalent bond between Al(s) and Cu(s), atoms is much stronger than the metallic bonding within Al(s).
b. The relatively different radi of the metals result in the atoms being in a more disordered arrangement, so the atoms are unable to slide past one another as easily.
Two different ionic compounds each contain only copper and chlorine. Both compounds are powders, one white and one brown. An elemental analysis is performed on each powder. Which of the following questions about the compounds is most likely to be answered by the results of the analysis? a. What is the density of each pure compound? b. What is the formula unit of each compound? c. What is the chemical reactivity of each compound? d. Which of the two compounds is more soluble in water?
b. What is the formula unit of each compound?
Consider an alloy containing Cu and one other element. Which of the following would correctly describe an alloy containing Cu? a. Zn would form an interstitial alloy with it, with Cu fitting in the small gaps within a Zn array. b. Zn would form a substitutional alloy with it, due to their similar radii. c. C would form a substitutional alloy with it,, with Cu fitting in the small gaps within a Cu array. d. C may form an interstitial alloy with it if a percentage of Cu atoms are replaced by C atoms in a predictable pattern.
b. Zn would form a substitutional alloy with it, due to their similar radii.
3.22 g sample of an unknown hydrate of sodium sulfate, NazSO4 • xH2O(s), is heated to drive off the water. The mass of the anhydrous NazSO4(s) (molar mass 142 g) a. 1.8 b. 6 c. 10 d. 20
c. 10
Which of the following best represents the ground-state electron configuration for an atom of selenium? a. 1s?2s 2p63s?3p3 b. 1s?25?2p3s?3p c. 15?2s22p63523p4s3d104p4 d. 1s?2s2p63s23p64s23d104p5
c. 15?2522p63523p4s3d104p4
Which of the following is the ground-state electron configurations of the fluoride ion? a. 1s2s522p b. 1s?2s22p5 c. 1s2s22p6 d. 1s?2572p63s?3p
c. 1s2s22p6
In 1.00 mol of potassium zirconium sulfate trihydrate, KaZr(SO4)4 • 3 H2O, there are a 1.81 x 1024 hydrogen atoms b. 6.02 × 1023 sulfur atoms c. 2.41 x 1024 potassium atoms d. 4 moles of oxygen atoms e. 4 moles of zirconium atoms
c. 2.41 x 1024 potassium atoms
Shown below are the photoelectron spectra of nitrogen and fluorine. Given the data in the two spectra, what do you expect the binding energy of the 1s electrons in oxygen to be? a. 0 - 50 eV b. 50 - 400 eV c. 400 - 700 eV b. 700 - 1000 eV
c. 400 - 700 eV
Which of the following sets of elements and/or ions contain species that are isoelectronic? a. F, Ne, Na, 02- b. F, Ne, Na*, Mg2+ c. Al3+, S2-, Ar, K+ d. p3-, S2-, Ar, Ca2+
c. Al3+, S2-, Ar, K+
Which of the following elements has the highest electronegativity? a. Cs b. Ag c. Br d. Se
c. Br
The radius of the S2- ion is 184 pm, while the radius of the Clion is 181 pm. Which of the following accounts for why this is true? a. S2- has more electrons shielding the pull of the nucleus compared to CI b. S2- has more electrons than CI. c. Cr has a greater effective nuclear charge than S2- d. The additional electrons in S2- add another shell to the ion.
c. Cr has a greater effective nuclear charge than S2-
2. To make Au stronger and harder, it is often alloyed with other metals, such as Cu and Ag. Consider two alloys, one of Au and Cu and one of Au and Ag, each with the same mole ratio of Au. If the Au/Cu alloy is harder than the Au/Ag alloy, then which of the following is the best explanation based on the table above. a. Cu has two common oxidation states, but Ag has only one. b. Cu has a higher melting point than Au has, but Ag has a lower melting point than Au has. c. Cu atoms are smaller than Ag atoms, thus the interfere more with the displacement of atoms in the alloy. d. Cu atoms are less polarizable than Au or Ag atoms, thus Cu has weker interparticle forces.
c. Cu atoms are smaller than Ag atoms, thus the interfere more with the displacement of atoms in the alloy.
In metallic bonding. what is the dominant form of attraction between the lattice of positive ions and the sea of delocalized electrons? a. Gravitational b. Magnetic c. Electrostatic d. Covalent
c. Electrostatic
Which statement describes the energy changes that occur as bonds are broken and formed during a chemical reaction? a. Energy is absorbed when bonds are both broken and formed. b. Energy is released when bonds are both broken and formed. c. Energy is absorbed when bonds are broken, and energy is released when bonds are formed. d. Energy is released when bonds are broken, and energy is absorbed when bonds are formed.
c. Energy is absorbed when bonds are broken, and energy is released when bonds are formed.
The melting point of MgO is higher than that of Na. Explanations for this observation include which of the following? I. Mg2+ is more positively charged than Na+ II. O2- is more negatively charged than F+ III. The O2- ion is smaller than the F ion. a. I only b. Iand ll only c. I and III only d. II and II only e. I and II and III
c. I and III only
The elements I and Te have similar average atomic masses. A sample that was believed to be a mixture of I and Te was run through a mass spectrometer, resulting in the data below. All the following statements are true. Which would be the best basis for concluding that the sample was pure Te? a. Te forms ions with a -2 charge, whereas I forms ions with a -1 charge. b. Te is more abundant than I in the universe. c. I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope. d. I has a higher first ionization energy than Te.
c. I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope.
Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound? a. It has the formula XZ2 b. It does not dissolve in water. c. It contains ionic bonds. d. It contains covalent bonds.
c. It contains ionic bonds.
Which of the following correctly indicates whether the solid represented by the particulate model shown opposite conducts electricity and explains why or why not? a. It conducts electricity because it is made of negative ions. b. It conducts electricity because it is made of particles of different sizes. c. It does not conduct electricity because its ions cannot move freely within the solid. d. It does not conduct electricity because there are small spaces between the particles.
c. It does not conduct electricity because its ions cannot move freely within the solid.
Shown in the diagram are the electronic structures of lithium and calcium atoms. The melting temperature of lithium is 181°C, while that of calcium is 842°C. Based on the electronic structures of the atoms and the strength of their metallic bonds, explain this difference in melting temperature Ca a. Metallic bonds are stronger in lithium as the valence electrons are closer to the nucleus, so more thermal energy is needed to break up the metal lattice. b. Metallic bonds are stronger in lithium as there are fewer valence electrons. so more thermal energy is needed to break up the metal lattice. c. Metallic bonds are weaker in lithium as there are fewer valence electrons, so less thermal energy is needed to break up the metal lattice d. Metallic bonds are stronger in lithium as there are more valence electrons, so more thermal energy is needed to break up the metal lattice
c. Metallic bonds are weaker in lithium as there are fewer valence electrons, so less thermal energy is needed to break up the metal lattice
The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.) a. Na+(g) + CI-(g) b. Cs+(g) + Br (g) c. Mg2+(g) + O2-(g) d. Ca2+ + O2-?
c. Mg2+(g) + O2-(g)
Of the following single bonds, which is the LEAST polar? a. N-H b. H-F c. O-F D. O-H
c. O-F
The first ionization energy for nitrogen is 1420 kJ/mol and oxygen is 1314 kJ/mol. Which of the following is the best explanation for this data? a. Oxygen has more electron-electron repulsions in its p orbital. b. Oxygen has more core electrons shielding its electrons from the Coulombic attraction from the nucleus. c. Oxygen has more electrons that are farther away from the nucleus than nitrogen. d. This is an anomaly in the data since most ionization energy values increase across the periodic table.
c. Oxygen has more electrons that are farther away from the nucleus than nitrogen.
Which of the following atoms would be BEST substitute for Cu in the formation of a substitutional alloy, if the atomic radius of Cu is 145 pm? a. O: 48 pm b. C: 67 pm c. Sn: 145 pm d. Au: 174 pm
c. Sn: 145 pm
The table opposite shows the first ionization energy and atomic radius of several elements. Which of the following best helps to explain the deviation of the first ionization energy of oxygen from the overall trend? a. The atomic radius of oxygen is greater than the atomic radius of fluorine. b. The atomic radius of oxygen is less than the atomic radius of nitrogen. c. There is repulsion between paired electrons in oxygen's 2p orbitals. d. There is attraction between paired electrons in oxygen's 2p orbitals.
c. There is repulsion between paired electrons in oxygen's 2p orbitals.
Which of the following is the best description of delocalized electrons in metallic bonding? a. Core electrons bound to metal ions b. Core and valence electrons that can move freely between metal ions c. Valence electrons that can move freely between metal ions d. Valence electrons bound to metal ions
c. Valence electrons that can move freely between metal ions
Which of the following best helps to explain why the electronegativity of Cl is less than that of F? a. The mass of the Cl atom is greater than the mass of the F atom. b. The Cl nucleus contains more protons than the F nucleus contains. c. When Cl and F form bonds with other atoms, the CI bonding electrons are more shielded from the positive CI nucleus than the F bonding electrons are shielded from the positive F nucleus. d. Because CI is larger than F, the repulsions among electrons in the valence shell of CI are less than the repulsions among electrons in the valence shell of F.
c. When Cl and F form bonds with other atoms, the CI bonding electrons are more shielded from the positive CI nucleus than the F bonding electrons are shielded from the positive F nucleus.
What is the electron configuration of V2+? a. [Ar]4s23d3 b. [Ar]4s13d4 c. [Ar]3d3 d. [Ar]4s23d1
c. [Ar] 3d3
Which of the following statements best accounts for peak A being far to the left of peaks B and C: a. the electron configuration of neon is 1s?2s 2p6. b. neon has 8 electrons located in its valence shell. c. core electrons of an atom experience a much higher effective nuclear charge than valence electrons. d. peaks B and C show first ionization energies of electrons in neon, whereas peak A shows the second ionization energy of neon.
c. core electrons of an atom experience a much higher effective nuclear charge than valence electrons.
A particle-level diagram of a metallic element is shown opposite. Typically, metals are both malleable and ductile. The best explanation for these properties is that the electrons involved in bonding among metal atoms are: a. unequally shared and form nondirectional bonds b. unequally shared and form highly directional bonds c. equally shared and form nondirectional bonds d. equally shared and form highly directional bonds
c. equally shared and form nondirectional bonds
Within a metal, the vacant orbitals in the atoms' outer energy levels: a. repel valence electrons. b. attract other metal atoms. c. overlap. d. diffract light.
c. overlap.
Which of the following ground-state electron configurations represents the atom that has the lowest first-ionization energy? a. 152251 b. 1522522p2 c. 15?252206 d. 1s22s22p63s'
d. 1s22s22p63s' , most electrons
The first ionization energy for Na is 495 kJ/mol. The BEST estimate for sodium's second ionization energy would be: a. 367 kJ/mol b. 584 kJ/mol c. 690 kJ/mol d. 4560 kJ/mol
d. 4560 kJ/mol ... becomes noble gas, very high
In the Lewis structure of formic acid, HCOOH, how many bonding pairs and lone pairs of electrons are prese a. 4 bonding, 2 lone b. 4 bonding, 5 lone c. 5 bonding, O lone d. 5 bonding, 4 lone
d. 5 bonding, 4 lone
An experiment is performed to measure the mass percent of CaCOs(s) in eggshells. Five different samples of CaCOss) of known mass react with an excess of 2.0 M HClag) in identical sealed, rigid reaction vessels. The pressure of he gas proouceds measured win a pressure gauge atached o me reaction vessel, since me reactions exoteric me reaction system is cooleo to ns onginartemperature before te pressure is recorded The experimental dala are used to creale tre Caloraton Iine befou 5 Ca Coz + 2.0M HCkag) The experiment is repeated with an eggshell sample, and the experimental data are recorded in the table below. The mass percent of CaCOss) in the eggshell sample is closest to a. 30% b. 45% c. 60% d. 75%
d. 75%
To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small pre-weighed sample in HNO3(ag). Ag*(ag) and Cu?*(ag) ions form in the solution. Which of the following should be the next step in the analytical process? a. Centrifuging the solution to isolate the heavier ions b. Evaporating the solution to recover the dissolved nitrates c. Adding enough base solution to bring the pH up to 7.0 d. Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions
d. Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions
Bonding is the interplay between which simultaneous occurrences? a. Maximizing attractions between electrons and nuclei b. Minimizing repulsions between electrons Minimizing the energy of the system d. All of the above
d. All of the above
A triple bond is found in which of the following species? 1. CO II. C2H2 III. CN a. I only b. II only c. I and Il only d. I, II and III
d. I, II and III
Consider the simulated PES spectrum below, showing the energy required to remove a 1s electron from an isolated nitrogen atom (red) and an isolated oxygen atom (blue). Which of the following BEST accounts for the peak in the nitrogen atom being to the right of the peak for the oxygen atom? a. Nitrogen atoms have a half-filled p sublevel. b. There are more electron-electron repulsions in oxygen atoms than nitrogen atoms. c. Electrons in the p sublevel of oxygen atoms provide more shielding than do electrons in the p sublevel of nitrogen. d. Nitrogen atoms have a smaller nuclear charge than do oxygen atoms.
d. Nitrogen atoms have a smaller nuclear charge than do oxygen atoms.
To determine the percentage of water in a hydrated salt, a student heated a 1.2346 g sample of the salt for 30 minutes; when cooled to room temperature, the sample weighed 1.1857 g. After the sample was heated for an additional 10 minutes and again cooled to room temperature, the sample weighed 1.1632 g. Which of the following should the student do next? a. Use the smallest mass value to calculate the percentage of water in the hydrated salt. b. Repeat the experiment with a new sample of the same mass and average the results. c. Repeat the experiment with a new sample that has a different mass. d. Reheat the sample until its mass is constant. e. Use the average of the mass values obtained after the two heatings to calculate the percentage of water in the hdrated salt.
d. Reheat the sample until its mass is constant.
In which species is the central atom NOT surrounded by exactly 8 valence electrons? a. BF4- b. NCI3 c. PCI4+ d. SF4
d. SF4
In which species does the central atom have one or more lone pairs of valence electrons? a. AICI4- b. CO2 c. PC4+ d. SO2
d. SO2
The table at right shows the successive ionization energies of an element in kJ/mol. Which of the following elements could have this successive ionization energy data? a. Na b. Mg c. Al d. Si
d. Si
Which of the following scientific claims about the bond in the molecular compound HF is most likely to be true? a. There is a partial negative charge on the H atom. b. Electrons are shared equally between the H and F atoms. c. The bond is extremely weak d. The bond is highly polar
d. The bond is highly polar
The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds NaF and MgFz is shown in the table below. On the basis of Coulomb's law, which of the following best helps to explain the large difference between the lattice energies of NaF and MgF2? a. The solubility of MgFz is less than that of NaF. b. The electronegativity of Mg is greater than that of Na. c. c. The mass of the Mg cation is greater than that of the Na cation. d. The charge of the Mg cation is larger than that of the Na cation.
d. The charge of the Mg cation is larger than that of the Na cation.
A 5.0 g sample of MgCl2 may contain measurable amounts of other compounds as impurities. Which of the following quantities is (are) needed to determine that the sample is pure MgCI2? a. The color and density of the sample b. The mass of Mg in the sample only c. The number of moles of Cl in the sample only d. The mass of Mg and the mass or clin the sample
d. The mass of Mg and the mass of Cl the sample
sample of a solid labeled as NaCI may be impure. A student analyzes the sample and determines that it contains 75 percent chlorine by mass. Pure NaCI(s) contains 61 percent chlorine by mass. Which of the following statements is consistent with the data? a. The sample contains only NaCI(s) b. The sample contains NaCI(s) and Nals) c. The sample contains NaCI(s) and KCI(s) d. The sample contains NaCI(s) and LiCI(s)
d. The sample contains NaCI(s) and LiCI(s)
Which of the following best helps to explain why the electron affinity of Br has a greater magnitude than that of 1? a. Br has a lower electronegativitv than I. b. Br has a lower ionization energy than I. c. An added electron would go into a new shell in Br but not in I. d. There is a greater attraction between an added electron and the nucleus in Br than in I.
d. There is a greater attraction between an added electron and the nucleus in Br than in I.
6. If the binding energy of an electron is between 0 - 10 eV, it can be assumed that the electron originated in: a. an s orbital b. a p orbital c. a core orbital d. a valence orbital
d. a valence orbital
The photoelectron spectrum below shows the binding energies for all electrons in neutral element Z: What is the identity of element Z? a. boron b. carbon c. neon d. magnesium
d. magnesium
A solid substance is an excellent conductor of electricity. The chemical bonds in this substance are most likely a. ionic, because the valence electrons are shared between atoms. b. ionic, because the valence electrons are mobile. c. metallic, because the valence electrons are stationary. d. metallic, because the valence electrons are mobile.
d. metallic, because the valence electrons are mobile.
Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy? a. 1s?2522p63s?3p1 b. 1s?222p63s?3p5 c. 1572572p6352 d. 1s?2s?2p3s1 e. 1s22s22p63s13p1
e. 1s22s22p63s13p1
The percentage of silver in a solid sample is determined gravimetrically by converting the silver to Ag aq) and precipitating it as silver chlonde. Failure to do which of the following could cause errors in the analysis? I Account for the mass of the weighing paper when the mass of the sample II Measure the temperaure during the preciptation reaction III wash me precipitate IV Heat the AgCI precipitate to constant mass a. I only b. I and Il c. I and IV d. I and III e. I, III and IV
e. I, III and IV
Which of the following compounds contains both ionic and covalent bonds? a. SO3 b. C2H5OH c. MgF2 d. H2S e. NH4CI
e. NH4CI
