Chapter 6
What does the line in the following example actually represent? H—H
(C) A and B
If a neutral atom loses one electron, what is the electrical charge of the atom?
+1
If a neutral atom gains two electrons, what is the electrical charge of the atom?
-2
How many nonbonding pairs of electrons are in the following molecule? H—H
0 pairs
How many more electrons can fit within the valence shell of a hydrogen atom?
1
How many electrons are used to draw the electron-dot structure for acetylene?
10
How many electrons are used to draw the electron-dot structure for hydrogen peroxide?
14
How many electrons are used to draw the electron-dot structure for calcium chloride?
16
How many chloride ions (Cl1-) are needed to balance the positive charge of a barium ion (Ba2+)?
2
How many covalent bonds would the O atom usually form?
2
How many oxide ions (O2-) are needed to balance the positive charge of a titanium ion (Ti4+)?
2
How many covalent bonds will the N atom usually form?
3
How many valence electrons does boron (B, atomic no. = 5) have?
3
How many valence electrons does gallium (Ga, atomic no. = 31) have?
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
How many substituents are on the carbon atom in CH4?
4
How many substituents are on the nitrogen atom in NH4+?
4
How many valence electrons does bromine (Br, atomic no. = 35) have?
7
Germanium chloride has only two atoms surrounding the central germanium atom. Why then is the germanium chloride molecule bent?
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.
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
Atoms of nonmetallic elements form covalent bonds, but they can also form ionic bonds. How is this possible?
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 ionic compound is an example of a chemical compound.
Which of the following elements will most likely not form an ion at all?
Ar
An individual carbon-oxygen bond is polar. Yet carbon dioxide is nonpolar because ________.
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.
Which of the following bonds would be the most polar?
C-F
Which of the following bonds would be the least polar?
C-H
If carbonic acid (H2CO3) were to undergo ionization, what would one of the products be?
CO32-
Which of the following compounds would be ionic?
CaCl2
Which of the following elements will most likely form an ion with a -1 charge?
Cl
Which shows atoms in order of increasing electronegativity.
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?
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?
F
Which of the following molecules contains a polar covalent bond?
H-F
Which of the following molecules would contain a dipole?
H-F
Which of the following compounds has polar covalent bonds?
H20
Which of the following molecules is the most polar?
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.
What is the compound that forms if you react potassium and sulfur?
K2S
Which of the following elements has two valence electrons?
Mg
Which of the following elements will most likely form an ion with a +2 charge?
Mg
Which of the following molecules contains an ionic bond?
MgCl2
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?
Molecule A
List the following bonds in order of increasing polarity:
N-N < N-O < N-F < H-F
Which of the following molecules has the highest boiling point?
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.
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?
None of these statements describe polar molecules.
Which of the following elements has six valence electrons?
O
Which bond is most polar?
O-H
Which molecule is most polar?
O=C=S
Distinguish between a metal and a metal-containing compound.
Only one of these contains ionic bonds.
Phosphine is a covalent compound that contains phosphorus, P, and hydrogen, H. What is its chemical formula?
PH3
Which of the following elements will most likely form an ion with a -2 charge?
S
True or False: The more shells in an atom, the lower its electronegativity. Explain.
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 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 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 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 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 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?
They have a great tendency to lose electrons.
What is the name for the following polyatomic ion? CH3CO2-
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?
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?
all are correct
Ammonia is more polar than is borane because it ________.
all of the above
Which of the following would be an ion with a double positive charge?
an Mg atom that loses two electrons
Calcium fluoride, CaF2, is an example of ________.
an ionic compound
Polar molecules tend to be ________.
asymmetrical
What is the molecular shape of the SF2 molecule?
bent
What is the molecular shape of the water molecule?
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?
bent
An atom loses an electron to another atom. Is this an example of a physical or chemical change?
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, neither
The principal source of an atom's electronegativity is the ________.
effective nuclear charge
What surrounds the sulfur atom in SF4?
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 electron to share
The neon atom tends NOT to lose any electrons to form a compound because ________.
it already has a full valence shell
Electron dot structures are not so important for understanding ________.
metallic bonds
What is the name for the following polyatomic ion? PO43-
phosphate
What is the molecular shape of the ammonia molecule?
pyramidal
The neon atom tends NOT to gain any additional electrons because ________.
there is no more room available in its outermost occupied shell
The number of nonbonding (lone) electron pairs in the water molecule is ________.
two
The acronym VSEPR stands for ________.
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
