CHEM 151 Exam 4 with |! |! |! |! |!
verified detailed solutions |! |!
Ionic compound - Correct answer ✔composed of positive and negative ions
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that are combined so that the numbers of positive and negative charges are
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equal
What types of ions (anions = - or cations = +) do metals form? Justify your
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reasoning. - Correct answer ✔Metals have low electronegativities. Because of
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this, metals are more likely to give up (or lose) their electrons to become +
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ions (cations)
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Another way to justify this would be to use their electron configurations. Na =
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1s22s22p63s1 so the most likely ion to form would be one with a noble gas
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electron configuration or one with a filled valence shell. The easiest way to do
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that is to lose that one electron in the 3s. Losing electrons make the ion
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positive (cation). |!
What types of ions (anions = - or cations = +) do nonmetals form? Justify your
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reasoning. - Correct answer ✔Nonmetals have high electronegativities.
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Because of this, nonmetals are more likely to gain electrons to become - ions
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(anions).
Another way to justify this would be to use their electron configurations. F =
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1s 2 2s22p5 so the most likely ion to form would have a filled valence shell,
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which means F would add (acquire) one electron, making it F - .
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,How are ionic compounds different from covalent compounds? - Correct
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answer ✔Ionic compounds: |! |!
metal with a nonmetal |! |! |!
electrons are not shared in bonds |! |! |! |! |!
the metal will have a + charge and the nonmetal will have a - charge
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Covalent compounds: |!
nonmetals with nonmetals |! |!
electrons are shared in bonds |! |! |! |!
there may be partial charges from polar bonds
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What would be the formula of calcium fluoride? - Correct answer ✔CaF2
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Explanation:
Ca has a +2 charge. F has a -1 charge. So there must be 2 F per 1 Ca.
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In ionic compounds we always put the _______ first - Correct answer ✔Metal
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What do you think influences different properties of ionic compounds? What
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would change the melting temperature? What would impact the solubility? -
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Correct answer ✔Ion charge should be an obvious one. What would be
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another? Have you ever heard of Coulomb's law? |! |! |! |! |! |! |!
What would be the formula of aluminum sulfide? - Correct answer ✔Al2S3
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Explanation:
Al has a +3 charge. S has a -2 charge. So there must be 2 Al3+ and 3S2- to
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make it neutral |! |!
, We always put the metals first.
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What would be the formula of barium sulfide? - Correct answer ✔BaS
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Explanation:
Ba has a +2 charge. S has a -2 charge.
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What would be the formula of calcium chloride? - Correct answer ✔CaCl2
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Explanation:
Ca has a +2 charge. Cl has a -1 charge.
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There are also some polyatomic (poly = many; atomic = atoms) ions that you
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will need to know. List them: - Correct answer ✔OH- : hydroxide ion
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NO3- : nitrate ion
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CO32- : carbonate ion
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SO42- : sulfate ion|! |! |!
PO43- : phosphate ion
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NH 4 + : ammonium ion
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What would be the formula of calcium hydroxide? - Correct answer ✔Ca(OH)2
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Explanation:
You treat the polyatomic ion like a "package". You don't separate it. If there
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are two of them, you put parentheses around the "package" and a subscript
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to balance charges.
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verified detailed solutions |! |!
Ionic compound - Correct answer ✔composed of positive and negative ions
|! |! |! |! |! |! |! |! |! |! |!
that are combined so that the numbers of positive and negative charges are
|! |! |! |! |! |! |! |! |! |! |! |! |!
equal
What types of ions (anions = - or cations = +) do metals form? Justify your
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
reasoning. - Correct answer ✔Metals have low electronegativities. Because of
|! |! |! |! |! |! |! |! |! |!
this, metals are more likely to give up (or lose) their electrons to become +
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
ions (cations)
|!
Another way to justify this would be to use their electron configurations. Na =
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
1s22s22p63s1 so the most likely ion to form would be one with a noble gas
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
electron configuration or one with a filled valence shell. The easiest way to do
|! |! |! |! |! |! |! |! |! |! |! |! |!
that is to lose that one electron in the 3s. Losing electrons make the ion
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
positive (cation). |!
What types of ions (anions = - or cations = +) do nonmetals form? Justify your
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
reasoning. - Correct answer ✔Nonmetals have high electronegativities.
|! |! |! |! |! |! |! |! |!
Because of this, nonmetals are more likely to gain electrons to become - ions
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
(anions).
Another way to justify this would be to use their electron configurations. F =
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
1s 2 2s22p5 so the most likely ion to form would have a filled valence shell,
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
which means F would add (acquire) one electron, making it F - .
|! |! |! |! |! |! |! |! |! |! |! |!
,How are ionic compounds different from covalent compounds? - Correct
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answer ✔Ionic compounds: |! |!
metal with a nonmetal |! |! |!
electrons are not shared in bonds |! |! |! |! |!
the metal will have a + charge and the nonmetal will have a - charge
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
Covalent compounds: |!
nonmetals with nonmetals |! |!
electrons are shared in bonds |! |! |! |!
there may be partial charges from polar bonds
|! |! |! |! |! |! |!
What would be the formula of calcium fluoride? - Correct answer ✔CaF2
|! |! |! |! |! |! |! |! |! |! |!
Explanation:
Ca has a +2 charge. F has a -1 charge. So there must be 2 F per 1 Ca.
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
In ionic compounds we always put the _______ first - Correct answer ✔Metal
|! |! |! |! |! |! |! |! |! |! |! |!
What do you think influences different properties of ionic compounds? What
|! |! |! |! |! |! |! |! |! |! |!
would change the melting temperature? What would impact the solubility? -
|! |! |! |! |! |! |! |! |! |! |!
Correct answer ✔Ion charge should be an obvious one. What would be
|! |! |! |! |! |! |! |! |! |! |! |!
another? Have you ever heard of Coulomb's law? |! |! |! |! |! |! |!
What would be the formula of aluminum sulfide? - Correct answer ✔Al2S3
|! |! |! |! |! |! |! |! |! |! |!
Explanation:
Al has a +3 charge. S has a -2 charge. So there must be 2 Al3+ and 3S2- to
|! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |! |!
make it neutral |! |!
, We always put the metals first.
|! |! |! |! |!
What would be the formula of barium sulfide? - Correct answer ✔BaS
|! |! |! |! |! |! |! |! |! |! |!
Explanation:
Ba has a +2 charge. S has a -2 charge.
|! |! |! |! |! |! |! |! |!
What would be the formula of calcium chloride? - Correct answer ✔CaCl2
|! |! |! |! |! |! |! |! |! |! |!
Explanation:
Ca has a +2 charge. Cl has a -1 charge.
|! |! |! |! |! |! |! |! |!
There are also some polyatomic (poly = many; atomic = atoms) ions that you
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
will need to know. List them: - Correct answer ✔OH- : hydroxide ion
|! |! |! |! |! |! |! |! |! |! |! |!
NO3- : nitrate ion
|! |! |!
CO32- : carbonate ion
|! |! |!
SO42- : sulfate ion|! |! |!
PO43- : phosphate ion
|! |! |!
NH 4 + : ammonium ion
|! |! |! |! |!
What would be the formula of calcium hydroxide? - Correct answer ✔Ca(OH)2
|! |! |! |! |! |! |! |! |! |! |!
Explanation:
You treat the polyatomic ion like a "package". You don't separate it. If there
|! |! |! |! |! |! |! |! |! |! |! |! |! |!
are two of them, you put parentheses around the "package" and a subscript
|! |! |! |! |! |! |! |! |! |! |! |! |!
to balance charges.
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