Chem 1010 Ch 6
What does the line in the following example actually represent? H—H (A) a shared pair of electrons (B) a covalent bond (C) A and B (D) a pair of nonbonding electrons
(C) A and B
If a neutral atom loses one electron, what is the electrical charge of the atom? -1 +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
How many more electrons can fit within the valence shell of a hydrogen atom? 1 2 7 0
1
How many electrons are used to draw the electron-dot structure for acetylene? 5 8 10 14
10
How many electrons are used to draw the electron-dot structure for hydrogen peroxide? 4 7 8 14
14
How many electrons are used to draw the electron-dot structure for calcium chloride? 4 6 8 16
16
How many chloride ions (Cl1-) are needed to balance the positive charge of a barium ion (Ba2+)? 2 1 3 0
2
How many covalent bonds would the O atom usually form? 1 2 4 f6
2
How many oxide ions (O2-) are needed to balance the positive charge of a titanium ion (Ti4+)? 1 2 3 4
2
How many covalent bonds will the N atom usually form? 3 2 1 5
3
How many valence electrons does boron (B, atomic no. = 5) have? 1 2 3 4
3
How many valence electrons does gallium (Ga, atomic no. = 31) have? 1 6 3 31
3
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 × 1018 tons, how much gold is in the ocean? 3.0 × 1012 kg 3.0 kg 300 g 36 mg
3.0 × 1012 kg
How many substituents are on the carbon atom in CH4? 1 2 2 H2 4
4
How many substituents are on the nitrogen atom in NH4+? 1 3 5 4
4
How many valence electrons does bromine (Br, atomic no. = 35) have? 1 7 21 28
7
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.
Which covalent bond is more polar: a sulfur-bromine (S-Br) bond or a selenium-chlorine (Se-Cl) bond? 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 sulfur-bromine bond should be more polar because of a smaller difference in effective nuclear charge.
A selenium-chlorine bond should be more polar because of a greater difference in effective nuclear charge.
If you mix a typical aluminum ion (Al, atomic no. = 13) with a typical oxygen ion (O, atomic no. = 8), what compound is formed? Al2O3 Al3O2 Al3O Al2O2
Al2O3
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. 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.
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. An ionic compound is an example of a chemical compound.
An ionic compound is an example of a chemical compound.
Which of the following elements will most likely not form an ion at all? Na O Ar Mg
Ar
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 (C) the electron-pulls of the two oxygen atoms are equal and opposite B and C
B and C
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 bonds would be the most polar? C-F C-Cl C-Br C-I
C-F
Which of the following bonds would be the least polar? C-F C-O C-Cl C-H
C-H
If carbonic acid (H2CO3) were to undergo ionization, what would one of the products be? H- CO2 CO3- CO32-
CO32-
Which of the following compounds would be ionic? CS2 CF4 SO2 CaCl2 SF5
CaCl2
Which of the following elements will most likely form an ion with a -1 charge? Na S Ne Cl
Cl
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
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. 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.
Which of the following has the greatest number of nonbonding pairs of electrons? C H He F
F
Which of the following molecules contains a polar covalent bond? H-F Cl-Cl H-H F-F
H-F
Which of the following molecules would contain a dipole? H-F Cl-Cl H-H F-F
H-F
Which of the following compounds has polar covalent bonds? H2O CsF2 S8 Ne
H20
Which of the following molecules is the most polar? HF HCl CO
HF
How is it possible for a neutral molecule, such as water, to form an ion? 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.
What is the compound that forms if you react potassium and sulfur? K2S KS SP PS2
K2S
Which of the following elements has two valence electrons? Na Mg H Ne
Mg
Which of the following elements will most likely form an ion with a +2 charge? Na Mg Ne Si
Mg
Which of the following molecules contains an ionic bond? MgCl2 Cl2 SF3 Cl2O7
MgCl2
List the following bonds in order of increasing polarity: N-O < N-N < N-F < H-F 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 NH3 CH4 SH2
NH3
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. 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. None of these statements describe polar molecules.
None of these statements describe polar molecules.
Which of the following elements has six valence electrons? Be B C O
O
Which bond is most polar? H-N N-C C-C O-H
O-H
Which molecule is most polar? S=C=S O=C=O 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 PH2 PH3 PH4
PH3
Which of the following elements will most likely form an ion with a -2 charge? Na S Ne Mg
S
True or False: The more shells in an atom, the lower its electronegativity. Explain. Always true; the greater the number of shells in an atom, the lower the electronegativity. Always false; the greater the number of shells in an atom, the higher the electronegativity. Sometimes true and sometimes false; This holds true only within any one atomic group (vertical column). Sometimes true and sometimes false; This holds true only across any given period (row) of the periodic table.
Sometimes true and sometimes false; This holds true only within any one atomic group (vertical column).
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. 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.
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. 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.
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. 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 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.
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. 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.
What is the name for the following polyatomic ion? CH3CO2- triacetate monocarboxylate acetate acidic
acetate
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. all are correct
all are correct
Water and methane have about the same mass. Why is the boiling point of water so much higher than that of methane? The water molecule is less symmetrical than is the methane molecule. The oxygen of a water molecule has two lone pairs of electrons. The electronegativity difference between oxygen and hydrogen is greater than the electronegativity difference between carbon and hydrogen. 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 all of the above
all of the above
Which of the following would be an ion with a double positive charge? an Mg atom that gains two electrons an Mg atom that gains one electron an Mg atom that loses two electrons an Mg atom that loses one electron
an Mg atom that loses two electrons
Calcium fluoride, CaF2, is an example of ________. an ionic compound a metallic compound a covalent compound a polar covalent compound
an ionic compound
Polar molecules tend to be ________. symmetrical elongated asymmetrical diatomic
asymmetrical
What is the molecular shape of the SF2 molecule? linear bent tetrahedral octahedral
bent
What is the molecular shape of the water molecule? pyramidal 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
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
Classify the following bonds as ionic, covalent, or neither O with F; Ca with Cl; Na with Na covalent, ionic, covalent ionic, covalent, neither neither, ionic, covalent covalent, ionic, neither
covalent, ionic, neither
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 effective nuclear charge the kinetic energy electrons have orbiting the nucleus
effective nuclear charge
What surrounds the sulfur atom in SF4? four substituent fluorine atoms 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 has only one electron to share loses its valence electron so readily has such a strong electronegativity
has only one electron to share
The neon atom tends NOT to lose any electrons to form a compound because ________. 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
Electron dot structures are not so important for understanding ________. ionic bonds metallic bonds covalent bonds polar covalent bonds
metallic bonds
What is the name for the following polyatomic ion? PO43- phosphate phosphorus oxide phosphinate trioxo phosphoride
phosphate
What is the molecular shape of the ammonia molecule? pyramidal bent tetrahedral T-shaped
pyramidal
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 there is no more room available in its outermost occupied shell
there is no more room available in its outermost occupied shell
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 valence shell electron pair repulsion valentia sia electronus partium resonancius
valence shell electron pair repulsion
When is the electronic geometry of a molecule not the same as its molecular shape? 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
