Atomic structure, proton, electron, etc PDF

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Atomic structure and properties

1. According to the information in the table above, a 1.00 g sample of which of the following contains the greatest mass of oxygen? A. Na2O

B. MgO

C. K2O

D. CaO

2. The table above 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. 3. Which of the following best helps to account for the fact that the F- ion is smaller than the O2- ion? A. F- has a larger nuclear mass than O2- has. -

2-

C. F has more electrons than O has.

B. F- has a larger nuclear charge than O2- has. D. F- is more electronegative than O2- is.

F. F- is more polarizable than O2- has. 4. 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 [From the elemental analysis, the moles of copper and chlorine can be calculated, then the mole ratio can be calculated.]

5.To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small preweighed sample in HNO3(aq). Ag+(aq) and Cu2+(aq) 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

6. Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains exactly two unpaired electrons A. S

B. Ca C. Ga D. Sb.

E. Br

7. Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains only one electron in the highest occupied energy sublevel A. S B. Ca C. Ga D. Sb. E. Br

8. For element X represented above, which of the following is the most likely explanation for the large difference between the second and third ionization energies? A. The effective nuclear charge decreases with successive ionizations. B. The shielding of outer electrons increases with successive ionization C. The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were. D. The ionic radius increases with successive ionizations. 9.An experiment is performed to measure the mass percent of CaCO3(s) in eggshells. Five different samples of CaCO3(s) of known mass react with an excess of 2.0MHCl(aq) in identical sealed, rigid reaction vessels. The pressure of the gas produced is measured with a pressure gauge attached to the reaction vessel. Since the reaction is exothermic, the reaction system is cooled to its original temperature before the pressure is recorded. The experimental data are used to create the calibration line below.

The experiment is repeated with an eggshell sample, and the experimental data are recorded in the table below. Mass of eggshell sample

0.200g

Pressure prior to reaction

0.800atm

Pressure at completion of reaction

0.870atm

The mass percent of CaCO3(s) in the eggshell sample is closest to A. 30% B. 45% C.60% D.75% Answer D The difference in pressure is 0.870atm−0.800atm=0.070atm. According to the graph, this pressure corresponds to a mass of CaCO3(s) of 0.145g. The mass of eggshell used was 0.200g. The mass percent of CaCO3(s) in the eggshell was thus approximately 0.145g /0.200g×100=73%.

10. The mass spectrum of the element Sb is most likely represented by which of the following?

B.

A.

C.

D.

Sb, 121.75amu

11. Which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference? A. The first ionization energy of Al is greater than that of B because Al has a larger nuclear charge than B does. B. The first ionization energy of F is greater than that of O because O has a higher electronegativity than F has. C. The atomic radius of Ca is larger than that of Mg because the valence electrons in Mg experience more shielding than the valence electrons in Ca do. D. The atomic radius of Cl is smaller than that of S because Cl has a larger nuclear charge than S does. 12. In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00? A.

Cr O3

B.

Cr O 2

C. CrO

D.

C r2 O

E.

Cr 2 O 3

Cr:52, O:16

13. A group of students was asked to recover Cu(s) from a blue-green aqueous solution containing an unknown concentration of Cu2+(aq) . The students took a 100.0 mL sample of the solution and added an excess of 1.0 M Na3PO4(aq), causing the Cu2+(aq) to precipitate as Cu3(PO4)2(s), as shown in step 1 below. Step 1

The Cu3(PO4)2(s) was filtered, dried, and weighed. Then the Cu3(PO4)2(s) was dissolved in a 3.0 M HCl(aq) solution, as shown in step 2 below. Step 2

The students added a strip of Zn(s) to the solution to recover the Cu(s), as shown in step 3 below. Step 3

Finally, the Cu(s) was filtered, dried, and weighed.The mass of the Cu(s) produced in step 3 was slightly more than the mass predicted from the 3.8 g of Cu3(PO4)2(s) recovered from step 1. Which of the following could account for the discrepancy in the yield of Cu(s) from step 3 ? A. All of the Cu3(PO4)2(s) dissolved in the HCl(aq). B. Some of the Cu(s) adhered to the side of the funnel used to filter the solution. C. Some unreacted Zn(s) was mixed in with the Cu(s). D. Too much Na3PO4(aq) was added to the original Cu2+(aq) solution. 14. Which of the following best helps to explain why the electron affinity of Br has a greater magnitude than that of I? A. Br has a lower electronegativity than I does. B. Br has a lower ionization energy than I does. 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] Br has one less electron shell than I does, so, on average, an electron added to the outer shell of Br is closer to the nucleus and less shielded than an electron added to the outer shell of I

15. Which of the following best helps 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 Cl bonding electrons are more shielded from the positive Cl nucleus than the F bonding electrons are shielded from the positive F nucleus. D. Because C is larger than F, the repulsions among electrons in the valence shell of Cl are less than the repulsions among electrons in the valence shell of F [C] Electronegativity is based on the ability of atoms participating in bonding to attract bonding electrons to themselves. The smaller size and lower amount of shielding in F cause it to be more electronegative than Cl

16. The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum? A. Nitrogen atoms have a half-filled p subshell. B. There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms. C. Electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms. D. Nitrogen atoms have a smaller nuclear charge than oxygen atoms. 17. Which of the following ground-state electron configurations represents the atom that has the lowest first-ionization energy?

A.

2

1s 2s

1

2

2

1s 2s 2 p

B.

2

C.

2

2

1s 2s 2 p

6

2

2

6

D. 1 s 2 s 2 p 3 s

1

An electron in a 3s sublevel is farthest from the nucleus. Based on Coulomb’s law, this weakens the attractive force between the electron and the nucleus, making it easier to remove.

18. Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy? 2

2

6

2

A. 1 s 2 s 2 p 3 s 3 p D. 1 s 2 2 s 2 2 p 6 3 s1 (A) Cs

1

(B) Ag

2

2

6

2

B. 1 s 2 s 2 p 3 s 3 p

5

2

2

6

C. 1 s 2 s 2 p 3 s

2

E. 1 s 2 2 s 2 2 p 6 3 s1 3 p 1 (C) Pb (D) Br

(E) Se

19. Has the highest electronegativity A. Cs

B. Ag

D. Br

C. Pb

E. Se

20. Has the lowest first-ionization energy A. Cs

B. Ag

C. Pb

D. Br

E. Se

21.The elements in which of the following have most nearly the same atomic radius? A. Be, B, C, N D.C, P, Se, I

B. Ne, Ar, Kr, Xe

C. Mg, Ca, Sr, Ba

E. Cr, Mn, Fe, Co

22.A sample of a compound that contains only the elements C, H, and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and some NO2 . A possible empirical formula of the compound is A. CH2N

B. CH5N

C. C2H5N

D. C3H3N2

23. A sample of a compound contains 3.21 g of sulfur and 11.4 g of fluorine. Which of the Following represents the empirical formula of the compound? A. SF2

B. SF3

C. SF4

D. SF5

E. SF6

24. After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference? A. Strong initial heating caused some of the hydrate sample 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. D. The crucible was not heated to constant mass before use. E. Excess heating caused the dehydrated sample to decompose.

25. The ionization energies of an unknown element, X, are listed in the table above. Which of the following is the most likely empirical formula of a compound formed from element X and phosphorus, P ? A. XP

B.X3P

C. X3P2

D.X3P4

26. Silicon crystals are semiconductors. Which of the following is a correct reason for the increase in the conductivity of Si crystals when a small fraction of Si atoms are replaced with those of a different element? A. P atoms introduce additional mobile negative charges.

B. P atoms introduce additional mobile positive charges. C. Ge atoms have more electrons than Si atoms have. D. Ge atoms are much smaller than Si atoms. It recognizes that phosphorus atoms contain one additional valence electron over the silicon atoms that make up the bulk of the material, and that these additional mobile charges will increase the conductivity of the silicon material.

27.Which of the following represents the ground state electron configuration for the Mn3+ ion? (Atomic number Mn = 25) A. 1s2 2s22p6 3s23p63d4 2

2

6

2

6

8

D. 1s 2s 2p 3s 3p 3d 4s

B. 1s2 2s22p6 3s23p63d5 4s2 2

2

2

6

2

6

3

E. 1s 2s 2p 3s 3p 3d 4s

C. 1s2 2s22p6 3s23p63d2 4s2 1

28. The mass spectrum of an average sample of a pure element is shown in the figure above. Which of the following is the identity of the element? A. Y B. Zr C. Nb D.Th

29.The mass spectrum of a sample of a pure element is shown above. Based on the data, the peak at 26amu represents an isotope of which of the following elements? A. Al with 13 neutrons B. Mg with 14 neutrons C. Fe with 26 neutrons

D. Ti with 26 neutrons

Based on the relative abundances of each isotope, the average atomic mass of the element is closest to 24amu, which corresponds to the element Mg. The peak at 26amu represents the isotope of Mg with 12 protons and 14 neutrons.

30. Forms monatomic ions with 2-charge in solution A. F

B. S

C. Mg

D. Ar

E. Mn

31.A student is given two 10g samples, each a mixture of only NaCl(s) and KCl(s) but in different proportions. Which of the following pieces of information could be used to determine which mixture has the higher proportion of KCl(s) ? A. The volume of each mixture

B. The mass of Cl in each mixture

C. The number of isotopes of Na and K

D. The reaction of each mixture with water

Answer B Based on the average atomic masses of the elements, the mass proportion of Cl in KCl is less than it is in NaCl. The mixture that has the higher proportion of KCl will have the smaller mass of Cl

1

2

3

4

5

6

7

total mass of

Mass f C in

Mass of Mg

Mass of Ca

Molar mass

Molar mass

Molar mass

sample (g)

sample (g)

in sample (g) in ample (g)

of C (g/mol)

of Mg (g/mol

of Ca (g/mol)

) 98.5

12.0

2.4

36.1

12.0

24.3

40.1

32.A sample of carbonate rock is a mixture of CaCO3 and MgCO3. The rock is analyzed in a laboratory, and the results are recorded in the table above. Which columns in the table provide all the information necessary to determine the mole ratio of Ca to Mg in the rock? A. 1, 2, 5

B. 2, 5, 6

C. 3, 4, 6, 7

D. 2, 3, 4, 5

Answer C From the masses of Ca and Mg and their respective molar masses (i.e., columns 3, 4, 6, 7), the number of moles of Ca and Mg can be calculated. The ratio of these two numbers is the desired answer.

33.A student has two samples of NaCl, each one from a different source. Assume that the only potential contaminant in each sample is KCl. The student runs an experiment to determine the percent by mass of chlorine in each sample. From the results of this experiment alone, which of the following questions is most likely to be answered? A. Which sample has the higher purity? B. Which sample has the higher density? C. What is the source of the contaminants present in each of the samples? D. Which sample came from a salt mine, and which sample came from the ocean? Answer A For each sample, the percent of chlorine by mass can be compared to the percent of chlorine by mass of pure NaCl. The sample with the greater percent of chlorine by mass has the higher purity.

34. Which of the following numerical expressions gives the number of particles in 2.0g of Ne?

6.0 × 10 23 particles / mol 6.0 × 10 23 particles / mol B. 2.0 g 20.18 g /mol 2.0 g 20.18 g /mol (6.0 × 1023 particles / mol ) D. (6.0 × 1023 particles / mol ) C. 20.18 g /mol 2.0 g A.

35. The photoelectron spectrum for an unknown element is shown above. (a) Based on the photoelectron spectrum, identify the unknown element and write its electron configuration. (b) Consider the element in the periodic table that is directly to the right of the element identified in part (a). Would the 1s peak of this element appear to the left of, the right of, or in the same position as the 1speak of the element in part (a)? Explain your reasoning. a) The element is phosphorus, P. The electron configuration of P is 1s2 2s2 2p6 3s2 3p3. b) the1s peak would be to the left of the peak in the spectrum shown. the 1s electron is in a lower energy state (and thus has a larger binding energy) because the nucleus of the element that is directly to the right in the periodic table would have more protons (16) than the number of protons (15) in the element corresponding to the given spectrum.

36. The photoelectron spectra for H and He are represented above. Which of the following statements best accounts for the fact that the peak on the He spectrum is farther to the left and higher than the peak on the H spectrum? A. He has an additional valence electron in a higher energy level than the valence electron in H. B. He has a greater nuclear charge than H and an additional electron in the same energy level. C. He has a completely filled valence shell in which the electrons are a greater distance from the nucleus than the distance between the H nucleus and its electron. D. It takes longer for the electrons in He to be removed due to the higher nuclear mass of He. Answer B Correct. The He nucleus has two protons. The greater nuclear charge of He increases the attraction of its two electrons to the nucleus, increasing their binding energy, which moves the peak to the left. The peak is twice the height of the peak for H because there are twice as many electrons in the 1s orbital of the He atom than in the 1s orbital of the H atom.

37. The complete photoelectron spectrum of an element is given above. Which of the following electron configurations is consistent with the spectrum? A. 1s22s22p1 C. 1s22s22p63s23p6

B. 1s22s22p63s23p3 D. 1s22s22p63s23p64s23d5

Answer B. The leftmost peak in the spectrum has the highest energy and contains two electrons; this is the peak that corresponds to the 1s electrons. Moving to the right, the next peak is the 2s peak, then the 2p peak, and then the 3s peak. The last peak is the 3p peak, which contains only 3 electrons. The correct electron configuration 1s22s22p63s23p3.

38. The complete photoelectron spectrum for an element is shown above. Which of the following observations would provide evidence that the spectrum is consistent with the atomic model of the element? A. A neutral atom of the element contains exactly two electrons. B. The element does not react with other elements to form compounds. C. In its compounds, the element tends to form ions with a charge of +1.

D. In its compounds, the element tends to form ions with a charge of +3. Answer C The photoelectron spectrum indicates that the element has one valence electron, which means that element tends to form ions with a +1 charge.

39. If Na reacts with chlorine to form NaCl, which of the following elements reacts with Na to form an ionic compound in a one-to-one ratio, and why? A. K, because it is in the same group as Na.

B. Mg, because its mass is similar to that of Na.

C. Ar, because its mass is similar to that of Cl. D. Br, because it has the same number of valence elec...