PHSC 1: Ch.15

75) Which of the following molecules is most likely to show the strongest hydrogen bonding?

D) CH3OH

78) How many valence electrons does bromine (Br, atomic no. = 35) have?

A) 7

76) What is the main difference between a dipole-dipole interaction and a dipole-induced dipole interaction?

A) Both are similar, but one involves a temporary dipole created by a permanent dipole.

99) Which of the following has the greatest number of nonbonding pairs of electrons?

A) F

48) How is it possible for a neutral molecule, such as water, to form an ion?

A) It can combine with a hydrogen ion to form a positively charged species.

97) Which of the following elements will most likely form an ion with a +1 charge?

A) Na

100) Which bond is most polar?

A) O-H

47) Which molecule is most polar?

A) O=C=S

56) Distinguish between a metal and a metal-containing compound.

A) Only one of these contains ionic bonds.

90) Which would you expect to have a higher melting point: sodium chloride, NaCl, or cesium chloride, CsCl? Why?

A) The sodium chloride has a higher melting point because its ions are smaller, which allows oppositely charged ions to get closer.

19) Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?

A) They have a great tendency to lose electrons.

5) Which of the above substances would have the lowest boiling point?

A) a (O=C=O)

16) What is a molecule?

A) a group of atoms that are held together by covalent bonds

68) Which of the following is not a property of metal?

A) does not conduct heat well

31) Dipole-induced dipole forces of attraction exist between water and gasoline, and yet these two substances do not mix because water has such a strong attraction for itself. Which of the following compounds might best help to make these two substances mix into a single liquid phase?

A) the molecule on the far left because the O-H bond is polar and the carbon and hydrogen bonds are nonpolar

28) What molecule loses a proton to form the hydroxide ion, OH⁻?

C) the water molecule, H O 2

27) Which of the above substances would have the largest dipole?

C) c .. H-O-H ..

88) If a neutral atom loses one electron, what is the electrical charge of the atom?

B) +1

8) The charges with sodium chloride are all balanced-for every positive sodium ion there is a corresponding negative chloride ion. Since its charges are balanced, how can sodium chloride be attracted to water, and vice versa?

B) As a water molecule gets close to the sodium chloride it can distinguish the various ions and it is thus attracted to an individual ion by ion-dipole forces.

82) Why does an atom with many valence electrons tend to gain electrons rather than lose any?

B) Atoms with many valence electrons tend to have relatively strong forces of attraction between the valence electrons and the nucleus. This makes it easy for them to gain additional electrons.

61) Chlorine, Cl2, is a gas at room temperature, but bromine, Br2, is a liquid. Explain.

B) Bromine atoms are larger and this makes the formation of induced dipole-induced dipole attractions more favorable.

60) Which of the following substances contains F- ions?

B) CaF 2

89) Which of the following elements will most likely form an ion with a -1 charge?

B) Cl

67) How do the electron-dot structures of elements in the same group in the periodic table compare with one another?

B) Elements of the same group have the same number of valence electrons

15) Which of the following molecules is most likely to show a dipole-dipole interaction?

B) H S 2

62) Which of the following would have the highest boiling point?

B) I 2

94) What is the valence shell?

B) It is the outermost shell of electrons in an atom.

12) Why is it better to recycle metals than to mine more?

B) It takes far less energy to recycle.

13) What is the compound that forms if you react potassium and sulfur?

B) K S 2

92) Consider the boiling points of the following compounds and their solubilities in room-temperature water. Why does the solubilities in water go down as the boiling points of these alcohols go up.

B) Larger molecules are more attracted to one another by induced dipole-induced dipole as well as by dipole-dipole and dipole-induced dipole attractions.

95) What property of metal atoms account for many of the observed bulk phenomena seen in metal samples?

B) Metal atoms easily lose one or more outer electrons.

7) Why are ores so valuable?

B) Metals can be efficiently extracted from them.

51) Which of the following elements will most likely form an ion with a +2 charge?

B) Mg

33) If an ionic bond is stronger than a dipole-dipole interaction, how can water dissolve an ionic compound?

B) The ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it into the solution.

35) A substance consisting of which molecule shown below should have a higher boiling point?

B) The molecule on the right, C2H2Cl, because of electronegativity considerations.

18) Given that the total number of atoms on our planet remains fairly constant, how is it ever possible to deplete a natural resource such as a metal?

B) The problem is with the expense of collecting metal atoms that are uniformly dispersed.

57) What is happening at the molecular level when a polar molecule like water interacts with a typical sodium ion?

B) The water molecule aligns such that the oxygen interacts with the sodium.

1) Why is it so easy for a magnesium atom to lose two electrons?

B) These two electrons are well shielded from the nuclear charge.

66) Which of the following is the weakest?

B) an induced dipole-induced dipole attraction

42) The concept of a chemical bond is

B) how two or more atoms are held together.

22) Which of the following best describes ionic bonding?

B) one atom giving up some of its electrons to another atom

49) Many of the macroscopic properties of a compound depend on

C) how the atoms of the molecules are held together.

44) The neon atom tends not to lose any electrons because

C) of its relatively strong effective nuclear charge.

69) The source of an atomʹs electronegativity is the

C) positively charged atomic nucleus.

30) If a neutral atom gains two electrons, what is the electrical charge of the atom?

C) -2

50) If the following generic atom were to undergo ionization, what would be the charge of most likely product? . .. X . .

C) -3

11) How many nonbonding pairs of electrons are in the following molecule? H-H

C) 0 pairs

36) How many oxide ions (O^-2) are needed to balance the positive charge of a titanium ion (Ti^+4)?

C) 2

6) How many covalent bonds would the following atom usually form?

C) 3 . .. X . .

74) Which is more polar, a sulfur-bromine (S-Br) bond or a selenium-chlorine (Se-Cl) bond?

C) A selenium-chlorine bond should be more polar because of a greater difference in effective nuclear charge.

58) If you mix a typical aluminum ion (Al, atomic no. = 13) with a typical oxygen ion (O, atomic no. = 8), what compound is formed?

C) Al2O3

23) Atoms of nonmetallic elements form covalent bonds, but they can also form ionic bonds. How is this possible?

C) An ionic bond results when a nonmetallic elements gains an electron from a metallic element.

52) How are oxygen molecules attracted to water molecules?

C) As a water molecule is brought close to an oxygen molecule an induced dipole results in the O2 molecule causing the attraction.

63) Which of the following would have the highest boiling point?

C) C12H26

9) If carbonic acid (H2CO3) were to undergo ionization, what would one of the products be?

C) CO -2 3

70) Magnesium ions carry a 2+ charge, and chloride ions carry a 1- charge. What is the chemical formula for the ionic compound magnesium chloride?

C) MgCl2

53) List the following bonds in order of increasing polarity

C) N-N < N-O < N-F < H-F

84) Which of the following molecules has the highest boiling point?

C) NH3

85) Given the following diagram, describe what happens electronically between these two molecules.

C) Oxygen B becomes slightly positively charged due to the electrons on the water molecule.

86) Why doesnʹt the sodium atom gain seven electrons so that its third shell becomes the filled outermost shell?

C) Sodiumʹs nuclear charge is not strong enough to hold that many more electrons.

98) Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, Al2O3?

C) The aluminum oxide has a higher melting point because of the greater charges of the ions, and hence the greater force of attractions between them.

20) What property of alloys make them ideal for developing new materials?

C) The characteristics of the material change depending on how much of each component is present.

24) What needs to be done to convert a neutral nitrogen atom into an N^-3 species?

C) add three electrons

65) Which of the following molecules is polar?

C) c

39) If the following generic atom were to undergo ionization, what would be the charge of the most likely product? .X.

D) +2

29) How many more electrons can fit within the valence shell of a hydrogen atom?

D) 1

59) If the concentration of gold in seawater is 2.0 milligram per ton of sea water and the mass of the ocean is 1.5 × 10^18 tons, how much gold is in the ocean?

D) 3.0 × 10^12 kg

87) Which of the following elements will most likely not form an ion at all?

D) Ar

40) Which of the following bonds would be the most polar?

D) C-F

96) Which of the following would have the lowest melting point?

D) CF4

55) Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?

D) Ionic bonds are so much stronger than the molecular attractions between covalently bonded compounds.

25) Why is calcium fluoride, CaF2, a high melting point crystalline solid while stannic chloride, SnCl4, is a volatile liquid?

D) Ionic compounds formed by elements on opposite sides of the periodic table, like CaF 2, tend to have higher melting points than more covalently bonded structures, like SnCl 4.

41) Which of the following elements has two valence electrons?

D) Mg

46) Which of the following elements has six valence electrons?

D) O

21) Which of the following is a negative ion?

D) O^-2

91) Given the following diagram, describe what happens electronically between these two molecules.

D) Oxygen A becomes slightly positively charged due to the protons on the water molecule.

32) Which of the following elements will most likely form an ion with a -2 charge?

D) S

26) An individual carbon-oxygen bond is polar. Yet carbon dioxide, CO2, which has two carbon-oxygen bonds, is nonpolar because

D) Two of the above are reasonable. ( the molecule has an even number of electrons,the electron-pulls of the two oxygen atoms are equal and opposite,it has a greater symmetry.)

17) The boiling point of 1,4-butanediol is 230°C. Would you expect this compound to be soluble or insoluble in room-temperature water?

D) Water would be attracted to both ends of 1,4 butanediol, and it is infinitely soluble in water.

14) Does an ionic bond have a dipole?

D) Yes, the ionic bond is an example of a very strong dipole.

93) Which of the following describes an aqueous solution?

D) a mixture of some compound dissolved in water

54) There is more gold in 1 km^3 of the ocean than the amount of gold mined in all of recorded history. How come we do not mine the oceans?

D) all of the above ( It would take too much energy,It would cost too much,It is too dilute to separate.)

81) Water, H2O, and methane, CH4, have about the same mass and differ by only one type of atom.

D) all of the above (The water molecule is less symmetrical than is the methane molecule,The electronegativity difference between oxygen and hydrogen is greater than the electronegativity difference between carbon and hydrogen,The oxygen of a water molecule has two lone pairs of electrons.)

64) Which of the following substances is pure?

D) all of the above (an ionic compound consisting of sodium and chlorine ions,an element,a covalent compound consisting of one type of molecule)

80) Ammonia, NH3, is more polar than is borane, BH3 because it

D) all of the above (its hydrogens are not exactly opposite one another,has a lone pair of electrons,is less symmetrical than borane.)

4) Which of the following would be an ion with a double positive charge?

D) an Mg atom that loses two electrons

45) An atom loses an electron to another atom. Is this an example of a physical or chemical change?

D) chemical change involving the formation of ions

43) Which of the following is the correct electron dot structure for chlorine (atomic no. = 17)?

D) d .. .. Cl . ..

10) The separation of charges within a polar molecule is called a(n)

D) dipole.

73) Which of the following intermolecular forces best describes why molecules like sucrose (which has many OH groups) are very water soluble?

D) hydrogen bonding

79) How many valence electrons does gallium (Ga, atomic no. = 31) have?

E) 3

34) Which of the following molecules is most likely to show a dipole-dipole interaction?

E) A and B (CH3OH,)CH3SH)

38) What does the line in the following example actually represent? HH

E) A and B (a shared pair of electrons,a covalent bond)

2) If you mix a typical iodine ion (I, atomic no. = 53) with a typical barium ion (Ba, atomic no. = 56), what compound is formed?

E) BaI 2

37) Metals are often used for making designer jewelry because they

E) C and D (are shiny,are strong but can be bent.)

72) Which of the following statements describes a polar molecule?

E) None of these statements describe polar molecules. (Polar molecules have the weakest intermolecular interactions with ionic compounds,The electrons in the molecule are distributed evenly throughout the molecule,The molecules are usually not attracted to one another very strongly,The molecules have a high degree of symmetry.)

83) Which of the following is not an ion?

E) O2

3) MgCl crystals are composed of 2

E) a multitude of Mg^2+ ions and Cl- ions grouped together in a three-dimensional array with a 1:2 ratio of Mg^2+ to Cl-.

71) Which of the following is the correct electron dot structure for carbon (atomic no. = 6)?

E) e . . C . .

77) Which of the following is an ion?

E) none of the above (no HCl ,2 H2,Au + 3 Br2,Br2)