chemistry exam 2
How many valence electrons does gallium (Ga, atomic no. = 31) have? 1 6 3 31
3
How many substituents are on the carbon atom in CH4? 1 2 2 H2 Correct! 4
4
How many substituents are on the nitrogen atom in NH4+? 1 3 You Answered 5 Correct Answer 4
4
How many molecules of sucrose are in 0.5 00L of a 2.00 molar solution of sucrose? 3.01 × 1023 molecules of sucrose Correct! 6.02 × 1023 molecules of sucrose 12.04 × 1023 molecules of sucrose 1 gram
6.02 x 1023 molecules of sucrose
How many valence electrons does bromine (Br, atomic no. = 35) have? 1 Correct! 7 21 28
7
How many electrons are used to draw the electron-dot structure for acetylene? 5 8 Correct! 10 14
10
How many electrons are used to draw the electron-dot structure for hydrogen peroxide? 4 7 8 Correct! 14
14
How many electrons are used to draw the electron-dot structure for calcium chloride? 4 6 You Answered 8 Correct Answer 16
16
How many chloride ions (Cl1-) are needed to balance the positive charge of a barium ion (Ba2+)? Correct! 2 1 3 0
2
How many covalent bonds would the O atom usually form? 1 Correct! 2 4 6
2
How many oxide ions (O2-) are needed to balance the positive charge of a titanium ion (Ti4+)? 1 Correct! 2 3 4
2
If a neutral atom loses one electron, what is the electrical charge of the atom? -1 Correct! +1 -2 +2
+1
If a neutral atom gains two electrons, what is the electrical charge of the atom? -1 +1 -2 +2
-2
How many nonbonding pairs of electrons are in the following molecule? H—H 1 pair 6 pairs 0 pairs 8 pairs
0 pairs
If you need 3.01 × 1023 molecules of sucrose, how many liters of a 4.00 molar solution would you need? Correct! 0.125 L 0.250 L 4.00 L 1.00 L
0.125L
How many more electrons can fit within the valence shell of a hydrogen atom? Correct! 1 2 7 0
1
Germanium chloride has only two atoms surrounding the central germanium atom. Why then is the germanium chloride molecule bent? There is a covalent bond between the two chlorine atoms. A lone pair of electrons on germanium pushes it to this orientation. Lone pairs of electrons on the chlorine atoms push it to this orientation. It is bent only periodically as it swings between both bent and linear shapes.
A lone pair of electrons on germanium pushes it to this orientation
If you mix a typical aluminum ion (Al, atomic no. = 13) with a typical oxygen ion (O, atomic no. = 8), what compound is formed? Correct! Al2O3 Al3O2 Al3O Al2O2
AI2O3
Which of the following bonds would be the most polar? C-F C-Cl C-Br C-I
C-F
An individual carbon-oxygen bond is polar. Yet carbon dioxide is nonpolar because ________. (A) the molecule has an even number of electrons (B) it's symmetry You Answered (C) the electron-pulls of the two oxygen atoms are equal and opposite Correct Answer B and C
B and C
If you mix a typical iodine ion (I, atomic no. = 53) with a typical barium ion (Ba, atomic no. = 56), what compound is formed? Correct! BaI2 BaI Ba2I Ba2I2
BaI2
Three kids sitting equally apart around a table are sharing jelly beans. One of the kids named Billy, however, tends only to take jelly beans and only rarely gives one away. If each jelly bean represents an electron, who ends up being slightly negative? Who ends up being slightly positive? Billy ends up being slightly negative, while the two other kids are both slightly positive. Billy ends up being slightly positive, while the two other kids are both slightly negative. One of the two kids other than Billy ends up slightly negative, but Billy and the third kid will both end up slightly positive. One of the two kids other than Billy ends up slightly positive, but Billy and the third kid will both end up slightly negative.
Billy ends up being slightly negative, while the two other kids are both slightly positive
Which of the following would have the weakest induced dipole-induced dipole interactions? Correct! C6H14 C8H18 C10H22 C12H26 not enough information given
C6H14
Which of the following molecules is most likely to show a hydrogen bonding interaction? Correct! (A) CH3OH (B) CH3SH (C) CH4 (D) H-C-C-H (E) A, B and C
CH3OH
Which of the following elements will most likely form an ion with a -1 charge? Na S Ne Cl
CI
If carbonic acid (H2CO3) were to undergo ionization, what would one of the products be? H- CO2 CO3- Correct! CO32-
CO32-
Which of the following compounds would be ionic? CS2 CF4 SO2 CaCl2 SF5
CaCI2
Which shows atoms in order of increasing electronegativity. Cs, Y, Ga, P, O, F F, O, Cs, Y, Ga, P Cs, F, Ga, O, P, Y
Cs, Y, Ga, P, O, F
Which of the following has the greatest number of nonbonding pairs of electrons? C H He Correct! F
F
Which of the following is most likely to have the weakest induced dipole-induced dipole interaction? Cl2 Br2 Correct! F2 I2 All of the above have the same interactions.
F2
Which of the following molecules contains a polar covalent bond? Correct! H-F Cl-Cl H-H F-F
H-F
Which of the following molecules would contain a dipole? Correct Answer H-F You Answered Cl-Cl H-H F-F
H-F
Which of the following compounds has polar covalent bonds? Correct! H2O CsF2 S8 Ne
H2O
Which of the following molecules is the most polar? Correct! HF HCl CO
HF
Which of the following would have the highest boiling point? Cl2 Br2 F2 Correct! I2 not enough information given
I2
Which of the following elements has two valence electrons? Na Correct! Mg H Ne
Mg
Which of the following elements will most likely form an ion with a +2 charge? Na Correct! Mg Ne Si
Mg
Which of the following molecules contains an ionic bond? Correct! MgCl2 Cl2 SF3 Cl2O7
MgCI2
List the following bonds in order of increasing polarity: You Answered N-O < N-N < N-F < H-F Correct Answer N-N < N-O < N-F < H-F H-F < N-F < N-O < N-N N-N < N-O < H-F < N-F
N-N<N-O<N-F<H-F
Which of the following molecules has the highest boiling point? BH3 Correct! NH3 CH4 SH2
NH3
Which of the following elements will most likely form an ion with a +1 charge? Na Mg Al Si
Na
Which of the following elements has six valence electrons? Be B C Correct! O
O
Which bond is most polar? H-N N-C C-C Correct! O-H
O-H
Which molecule is most polar? S=C=S O=C=O Correct! O=C=S These all have the same polarity.
O=C=S
Phosphine is a covalent compound that contains phosphorus, P, and hydrogen, H. What is its chemical formula? PH PH_2 PH_3 PH_4
PH3
Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why. There is now a higher concentration of dissolved CO2 in the water. The nutrients in the water have been destroyed. Since some of the water was evaporated while boiling, the salts in the water are now more concentrated. This has a negative effect on the fish. Correct! The boiling process removes most of the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.
The boiling process removes most of the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.
Which covalent bond is more polar: a sulfur-bromine (S-Br) bond or a selenium-chlorine (Se-Cl) bond? Correct! A selenium-chlorine bond should be more polar because of a greater difference in effective nuclear charge. A selenium-chlorine bond should be more polar because of a smaller difference in effective nuclear charge. A sulfur-bromine bond should be more polar because of a greater difference in effective nuclear charge.
a selenium-chlorine bond should be more polar because of a greater difference in effective nuclear charge
What is a hydrogen bond? Correct! a special type of dipole-dipole attraction involving hydrogen bound to a highly electronegative atom a special type of dipole-dipole attraction involving hydrogen bound to any other atom a special type of dipole-dipole attraction involving hydrogen bound to another hydrogen atom a special type of attraction involving any molecules that contain hydrogens
a special type of dipole-dipole attraction involving hydrogen bound to a highly electronegative atom
What is the name for the following polyatomic ion? CH3CO2- triacetate monocarboxylate Correct! acetate acidic
acetate
How can you tell whether a sugar solution is saturated or not? Add more sugar, if it dissolves, it is saturated. There will be a precipitate if the water is heated. As long as there are more water molecules than sugar molecules, there is a saturated solution. Correct! Add more sugar. If it does not dissolve after mixing, the solution is saturated.
add more sugar if it does not dissolve after mixing the solution is saturated
There is more gold in 1 km3 of the ocean than the amount of gold mined in all of recorded history. How come we do not mine the oceans? It is too dilute to separate easily. It would take too much energy. It would cost too much. Correct! all are correct
all are correct
Ammonia is more polar than is borane because it ________. has a lone pair of electrons is less symmetrical than borane its hydrogens are not exactly opposite one another Correct! all of the above
all of the above
Which of the following is the strongest form of intermolecular attraction? a chemical bond Correct! an ion-dipole interaction a dipole-dipole interaction a dipole-induced dipole interaction an induced dipole-induced dipole interaction
an ion-dipole interaction
Atoms of nonmetallic elements form covalent bonds, but they can also form ionic bonds. How is this possible? This happens when one of the bonded nonmetallic elements has a strong electronegativity. It happens when one of the nonmetallic elements loses an electron to become a positive ion. An ionic bond results when a nonmetallic elements loses an electron to a metallic element. Correct! An ionic bond results when a nonmetallic elements gains electrons to form an ion.
an ionic bond results when a nonmetallic elements gains electrons to form an ion
Calcium fluoride, CaF2, is an example of ________. Correct! an ionic compound a metallic compound a covalent compound a polar covalent compound
an ionic compound
Is an ionic compound an example of a chemical compound, or is a chemical compound an example of an ionic compound? An chemical compound is an example of a ionic compound. Neither is an example of the other. Each is an example of the other. Correct! An ionic compound is an example of a chemical compound.
an ionic compound is an example of a chemical compound
Polar molecules tend to be ________. symmetrical elongated Correct! asymmetrical diatomic
asymmetrical
What is the molecular shape of the SF_2 S F 2 molecule? linear bent tetrahedral octahedral
bent
What is the molecular shape of the SF_2 S F 2 molecule? linear Correct Answer bent You Answered tetrahedral octahedral
bent
What is the molecular shape of the water molecule? pyramidal Correct! bent tetrahedral T-shaped linear
bent
What would be the shape of a molecule where the central atom has two nonbonding pairs while also covalently bonded to two other atoms? pyramidal bent tetrahedral linear
bent
What is the main difference between a dipole-dipole interaction and a dipole-induced dipole interaction? Correct! Both are similar, but one involves a temporary dipole created by a permanent dipole. Dipole-dipole interactions are weaker because the dipoles are permanent. Dipole-induced dipole interactions are stronger because the induced dipoles can be formed at any time. Both are identical.
both are similar but one involves a temporary dipole created by a permanent dipole
Hard water contains excessive amounts of ________. chlorine ions Correct! calcium ions hydrogen ions hydroxide ions
calcium ions
An atom loses an electron to another atom. Is this an example of a physical or chemical change? physical change involving the formation of negative ions chemical change involving the formation of neutral atoms physical change involving the formation of positive ions chemical change involving the formation of ions
chemical change involving the formation of ions
How is the solubility of a solid affected by temperature? As temperature goes up, the solubility goes up. As temperature goes down, the solubility goes down. As temperature goes up, the solubility goes down. As temperature goes down, the solubility goes up. Correct! It depends on the solid
depends on the solid
The principal source of an atom's electronegativity is the ________. repulsive force occurring among electrons within the same shell repulsive force occurring between electrons within neighboring shells Correct! effective nuclear charge the kinetic energy electrons have orbiting the nucleus
effective nuclear charge
Electron dot structures are not so important for understanding ________. ionic bonds Correct! metallic bonds covalent bonds polar covalent bonds
metallic bonds
How do the electron-dot structures of elements in the same group in the periodic table compare with one another? The structures differ by exactly two electrons between vertically consecutive elements. The number of valence shell electrons increases by one for each element from the top to the bottom of the group. Correct! Elements of the same group have the same number of valence electrons. The number of electrons in the electron-dot-structure will equal the group number for each element of the group.
elements of the same group have the same number of valence electrons
What surrounds the sulfur atom in SF4? four substituent fluorine atoms Correct! four substituent fluorine atoms plus one lone pair of electrons four substituent fluorine atoms plus two lone pairs of electrons four substituent fluorine atoms plus three lone pairs of electrons
four substituent fluorine atoms plus one lone pair of electrons
A hydrogen atom does not form more than one covalent bond because it ________. has only one shell of electrons Correct! has only one electron to share loses its valence electron so readily has such a strong electronegativity
has only one electron to share
Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds? Correct! Ionic bonds are so much stronger than the intermolecular attractions between covalently bonded compounds. Covalent bonds are not as strong as ionic bonds. As a solid, salts have a very organized crystalline structure which takes a lot of energy to break apart. Most covalent compounds have at least one weak bond in their structure that is easily broken when heat is added.
ionic bonds are so much stronger than the intermolecular attractions between covalently bonded compounds
The neon atom tends NOT to lose any electrons to form a compound because ________. Correct! it already has a full valence shell that would result in a negative ion its electrons are paired together within the same orbitals the ionization energy is so low
it already has a full valence shell
How is it possible for a neutral molecule, such as water, to form an ion? Correct! It can combine with a hydrogen ion to form a positively charged species. It can combine with a chloride ion to form a negatively charged species. It can fragment into protons and electrons.
it can combine with a hydrogen ion to form a positively charged species
Two liquids, A and B, have very different physical properties. A and B do not mix. A boils at 80°C and freezes at -30°C. B boils at 35°C and freezes at -100°C. Molecules of which are likely to have the largest dipole? Correct Answer molecule A molecule B Not enough information was given. You Answered Both have similar dipoles.
molecule A
Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals, burst when placed in fresh water? The dissolved ions provide a pressure that eventually bursts open the cell. Correct Answer More water molecules enter the cell than leave the cell. You Answered The fresh water acts to dissolve the blood cell wall. all are correct
more water molecules enter the cell than leave the cell
Take enough money away from your bank account and the bank will show a negative credit. Take an electron away from an atom, however, and the atom shows up positive. Explain. Electrons are already negative. Therefore, we know from basic math that subtracting a negative (number) from a neutral (atom), will make the result positive. Correct! Neutral atoms contain identically charged but oppositely signed protons and electrons. Removing one of the negative electrons results in an excess of positively charged protons. Removing an electron from an atom does not have the atom show up positive. It simply leaves the atom short one electron. Atoms are constantly exchanging electrons. Having an atom "show up positive" is only an expression indicating that it has taken its turn in the game of electron exchange.
neutral atoms contain identically charged but oppositely signed protons and electrons. Removing one of the negative electrons results in an excess of positively charged protons.
Which of the following statements describes a polar molecule? The electrons in the molecule are distributed evenly throughout the molecule. The molecules are usually not attracted to one another very strongly. Polar molecules have the weakest intermolecular interactions with ionic compounds. The molecules have a high degree of symmetry. Correct! None of these statements describe polar molecules.
none of these statements describe the polar molecules
Distinguish between a metal and a metal-containing compound. There is no distinction between the two. Correct! Only one of these contains ionic bonds. Only one of these contains covalent bonds. Only one of these occurs naturally.
only one of these contains ionic bonds
Red blood cells have a high concentration of dissolved ions. When placed into pure water they rupture. Why? Correct! Osmosis draws water into the cell until it pops. Water dissolves the cell membrane. Osmosis draws water out of the cell until it tears. The cells are not stable outside of a biological host.
osmosis draws water into the cell until it pops
What is the name for the following polyatomic ion? PO43- Correct! phosphate phosphorus oxide phosphinate trioxo phosphoride
phosphate
What is the molecular shape of the ammonia molecule? Correct! pyramidal bent tetrahedral T-shaped
pyramidal
Fluorine is a relatively ________. large atom soft atom Correct! small atom greenish atom
small atom
Describe what usually happens to a hot solution that is saturated with a solid as it cools. The solid that is dissolved comes out of the solution completely. The solid stays in the solution. Correct! Some of the solid comes out of the solution. The solution freezes.
some of the solid comes out of the solution
Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, Al2O3? The aluminum oxide has a higher melting point because it is a larger molecule and has a greater number of molecular interactions. NaCl has a higher melting point because it is a solid at room temperature. Correct! 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. The aluminum oxide has a higher melting point because of the covalent bonds within the molecule.
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
If an ionic bond is stronger than a dipole-dipole interaction, how can water dissolve an ionic compound? Correct! The ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it into the solution. The ionic bond is weakened by the ion-dipole interactions and ionic repulsion ejects the ions from the crystal. The ion-dipole interaction causes the ions to heat up and vibrate free of the crystal. The ions never overcome their interatomic attraction and therefore are not soluble.
the ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it into the solution
Which of the following accurately describes osmosis? Correct! The more concentrated solution absorbs water from the less concentrated solution. The less concentrated solution absorbs water from the more concentrated solution. The less concentrated solution gets more dilute. The ions migrate from the more concentrated solution to the less concentrated.
the more concentrated the solution absorbs water from the less concentrated solution
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? The problem remains that not everyone recycles as they should. Recycling only forestalls the inevitable depletion of metal resources. You Answered The atoms don't leave our planet, which is why naturally occurring materials never really reach the point of depletion. Correct Answer The problem is with the expense of collecting metal atoms that are uniformly dispersed.
the problem is with the expense of collecting metal atoms that are uniformly dispersed
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? The problem remains that not everyone recycles as they should. Recycling only forestalls the inevitable depletion of metal resources. The atoms don't leave our planet, which is why naturally occurring materials never really reach the point of depletion. Correct! The problem is with the expense of collecting metal atoms that are uniformly dispersed.
the problem is with the expense of collection metal atoms that are uniformly dispersed
What happens if you were to place a concentrated solution into a bag made of a semipermeable membrane and were to then suspend it in a very dilute solution? The size of the suspended bag would decrease. Correct! The size of the suspended bag would increase. The size of the bag would not change. The solutions would eventually reach the same concentration.
the size of the suspended bag would increase
Which would you expect to have a higher melting point: sodium chloride, NaCl, or cesium chloride, CsCl? Why? The cesium chloride has a higher melting point because larger ions of the same charge are able to attract more ions of the opposite charge. The cesium chloride has a higher melting point because its ions are smaller, which makes the charges more dense. The sodium chloride has a higher melting point because of the greater charges of the ions, and hence the greater force of attractions between them. Correct! The sodium chloride has a higher melting point because its ions are smaller, which allows oppositely charged ions to get closer.
the sodium chloride has a higher melting point because its ions are smaller which allows oppositely charged ions to get closer
Which of the following molecules can lose a proton to form the hydroxide ion, OH⁻? The oxygen molecule,O2 Correct! The water molecule, H2O The hydrogen peroxide molecule, H2O2 The hydrogen molecule
the water molecule, H2O
The valence electron of a sodium atom does not sense the full +11 of the sodium nucleus. Why not? There are two "non-valence shell" electrons shielding the sodium nucleus from sensing it. There are two inner shells of electrons containing ten electrons shielding the sodium nucleus from sensing it. Since the +11 charge is spread evenly around the entire spherical surface of the nucleus, the actual force of the charge in any given direction is greatly diminished. The distance from the nucleus to the loosely held lone valence electron varies greatly over time. So, the average sense of charge from the nucleus is considerably less than +11.
there are two inner shells of electrons containing ten electrons shielding the sodium nucleus from sensing it
The neon atom tends NOT to gain any additional electrons because ________. its nuclear charge is not great enough that would result in a positive ion of the repulsions they would experience with electrons in the same shell Correct! there is no more room available in its outermost occupied shell
there is no more room available in its outermost occupied shell
Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why? These atoms are too large to be able to come in close contact with other atoms. Correct! They have a great tendency to lose electrons. Their valence shells are already filled with electrons. They are on the wrong side of the periodic table.
they have a great tendency to lose electrons
The number of nonbonding (lone) electron pairs in the water molecule is ________. one two three four
two
The acronym VSEPR stands for ________. valence shell electron positive repulsion very significant electron pull resonance Correct! valence shell electron pair repulsion valentia sia electronus partium resonancius
valence shell electron pair repulsion
Cells at the top of a tree have a higher concentration of sugars than cells at the bottom. How might this fact assist a tree in moving water upward from its roots? Cells with high concentrations of sugar are more dense. As these cells migrate downwards, cells containing fresh water are able to migrate upwards. Correct! Water is pushed upwards by osmostic pressure. It doesn't. In fact, water makes it to the top of a tree because that is where the water molecules are being evaporated. Fresh water is drawn upwards to the sugar containing cells by way of dipole-dipole molecular interactions.
water is pushed upwards by osmotic pressure
When is the electronic geometry of a molecule not the same as its molecular shape? Correct! when one or more of the substituents is a lone pair of electrons when there are an odd number of electron pairs as substituents when there are an odd number of electrons surrounding the central atom The geometry of a molecule is always the same as its shape
when one or more of the substituents is a lone pair of electrons
When is the electronic geometry of a molecule not the same as its molecular shape? Correct! when one or more of the substituents is a lone pair of electrons when there are an odd number of electron pairs as substituents when there are an odd number of electrons surrounding the central atom The geometry of a molecule is always the same as its shape.
when one or more of the substituents is a lone pair of electrons