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11.10: Exercises

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    11.2:  Representing Valence Electrons with Dots

    1. Is it necessary for the first dot around an atomic symbol to go on a particular side of the atomic symbol?
    Answer

    No. The first dot can go on any side of the atomic symbol.

     

    1. What column of the periodic table has Lewis electron dot diagrams with two electrons?
    Answer

    IIA or 2

     

    1. What column of the periodic table has Lewis electron dot diagrams that have six electrons in them?
    Answer

    VIA or 16

     

    1. Draw the Lewis electron dot diagram for each element.
      1. strontium
      2. silicon
    Answer
    1. \(⋅\,\mathrm{Sr}\,⋅\)
    2.  \(\overset⬝{\underset⬝{⋅\,\mathrm{Si}\,⋅}}\)

     

    1. Draw the Lewis electron dot diagram for each element.
      1. krypton
      2. sulfur
    Answer
    1. \(\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{Kr}:}}\)
    2. \(\overset⬝{\underset{⬝\,⬝}{:\mathrm{S}\,⋅}}\)

     

    1. Draw the Lewis electron dot diagram for each element.
      1. potassium
      2. phosphorus
    Answer
    1. \(\mathrm K\,⋅\)
    2. \(\overset⬝{\underset⬝{:\mathrm{P}\,⋅}}\)

     

    1. Draw the Lewis electron dot diagram for each element.
      1. bromine
      2. gallium
    Answer
    1. \(\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{Br}\,⋅}}\)
    2. \(\overset⬝{\underset⬝{\mathrm{Ga}}}\,⋅\)

     

    11.3:  Ionic Bonds

    1. How many electrons does a Ba atom have to lose to have a complete octet in its valence shell?
    Answer

    2

     

    1. How many electrons does a Pb atom have to lose to have a complete octet in its valence shell?
    Answer

    4

     

    1. How many electrons does an Se atom have to gain to have a complete octet in its valence shell?
    Answer

    2

     

    1. How many electrons does an N atom have to gain to have a complete octet in its valence shell?
    Answer

    3

     

    1. Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: P, I, Mg, Cl, In, Cs, O, Pb, Co?
    Answer

    P, I, Cl, and O would form anions because they are nonmetals. Mg, In, Cs, Pb, and Co would form cations because they are metals.

     

    1. Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: Br, Ca, Na, N, F, Al, Sn, S, Cd?
    Answer

    Br, N, F, and S would form anions because they are nonmetals. Ca, Na, Al, Sn, and Cd would form cations because they are metals.

     

    1. Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:
      1. P
      2. Mg
      3. Al
      4. O
      5. Cl
      6. Cs
    Answer
    1. P3-
    2. Mg2+
    3. Al3+
    4. O2-
    5. Cl-
    6. Cs+

     

    1. Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:
      1. I
      2. Sr
      3. K
      4. N
      5. S
      6. Li
    Answer
    1. I-
    2. Sr2+
    3. K+
    4. N3-
    5. S2-
    6. Li+

     

    1. Name two ions with the same Lewis electron dot diagram as the Cl− ion.
    Answer

    S2- and P3-

     

    1. Draw the Lewis electron dot diagram for each ion.
      1. Mg2+
      2. S2−
    Answer
    1. Mg2+ (no electrons)
    2. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{S}:}}\right]^{2-}\)

     

    1. Draw the Lewis electron dot diagram for each ion.
      1. H+
      2. Br−
    Answer
    1. H+ (no electrons)
    2. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{Br}:}}\right]^-\)

     

    1. Draw the Lewis electron dot diagram for each ion.
      1. Al3+
      2. N3−
    Answer
    1. Al3+ (no electrons)
    2. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{N}:}}\right]^{3-}\)

     

    1. Write the Lewis symbols for each of the following ions:
      1. As3–
      2. I–
      3. Be2+
      4. O2–
      5. Ga3+
      6. Li+
      7. N3–
    Answer
    1. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{As}:}}\right]^{3-}\)
    2. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{I}:}}\right]^-\)
    3. Be2+ (no electrons)
    4. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{O}:}}\right]^{2-}\)
    5. Ga3+ (no electrons)
    6. Li+ (no electrons)
    7. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{N}:}}\right]^{3-}\)

     

    1. Many monatomic ions are found in seawater, including the ions formed from the following list of elements. Write the Lewis symbols for the monatomic ions formed from the following elements:
      1. Cl
      2. Na
      3. Mg
      4. Ca
      5. K
      6. Br
      7. Sr
      8. F
    Answer
    1. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{Cl}:}}\right]^-\)
    2. Na+ (no electrons)
    3. Mg2+ (no electrons)
    4. Ca2+ (no electrons)
    5. K+ (no electrons)
    6. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{Br}:}}\right]^-\)
    7. Sr2+ (no electrons)
    8. \(\left[\overset{⬝\,⬝}{\underset{⬝\,⬝}{:\mathrm{F}:}}\right]^-\)

     

    11.4:  Covalent Bonds

    1. How many electrons will be in the valence shell of H atoms when it makes a covalent bond?
    Answer

    2

     

    1. How many electrons will be in the valence shell of non-H atoms when they make covalent bonds?
    Answer

    8

     

    1. What is the Lewis electron dot diagram of I2? 
    Answer

    Linear structure of iodine showing a single covalent bond connecting the two iodine atoms together and three lone pair electron groups on each iodine.

     

    1. What is the Lewis electron dot diagram of H2S? 
    Answer

    Bent chemical structure of hydrogen sulfide showing one covalent bond connecting each hydrogen to the central sulfur. Sulfur has two lone pair electron groups.

     

    1. What is the Lewis electron dot diagram of NCl3?
    Answer

    T-shaped structure of nitrogen trichloride showing a single covalent bond connecting each chlorine to the central nitrogen. Nitrogen has a single lone pair electron group and each chlorine has three lone pair electron groups.

     

    1. What is the Lewis electron dot diagram of SiF4? 
    Answer

    Chemical structure of silicone tetrafluoride showing a single covalent bond connecting each fluorine to the central silicone. Silicone has zero lone pair electron groups and each fluorine has three lone pair electron groups.

     

    11.6:  Writing Lewis Structures for Molecular Compounds

    1. Draw the Lewis structure for each substance.
      1. SF2
      2. C2Cl2 (assume two central atoms)
    Answer
    1. Bent chemical structure of sulfur difluoride showing a single covalent bond connecting each fluorine to the central sulfur. Sulfur has two lone pair electron groups and each fluorine has three lone pair electron groups.
    2. Linear structure of dichloroacetylene showing three covalent bonds connecting the center carbons together, and a single covalent bond connecting each outer chlorine to a carbon. Each carbon is connected to a single chlorine. Each chlorine has three lone pair electron groups and carbon has zero lone pair electron groups.

     

    1. Draw the Lewis structure for each substance.
      1. PI3
      2. CS2
    Answer
    1. T-shaped structure of phosphorus triiodide showing a single covalent bond connecting each iodine to the central phosphorus. Phosphorus has a single lone pair electron group and each iodine has three lone pair electron groups.
    2. Linear structure of carbon disulfide showing two covalent bonds connecting each sulfur to the central carbon. Each sulfur has two lone pair electrons and carbon has zero lone pair electrons.

     

    1. Draw the Lewis structure for each substance.
      1. GeH4
      2. ClF
    Answer
    1. Chemical structure of germanium tetrahydride showing a single covalent bond connecting each hydrogen to the central germanium. There are no lone pair electron groups.
    2. Linear structure of chlorine fluoride showing a single covalent bond connecting the atoms. Both chlorine and fluorine have three lone pair electrons each.

     

    1. Draw the Lewis structure for each substance.
      1. AsF3
      2. POCl
    Answer
    1. T-shaped structure of arsenic trifluoride showing a single covalent bond connecting each fluorine to the central arsenic. Arsenic has a single lone pair electron group and each fluorine has three lone pair electron groups.
    2. Bent structure of phosphoryl chloride showing two covalent bonds connecting oxygen to the central phosphorus and a single covalent bond connecting chlorine to the central phosphorus. Oxygen has two lone pair electron groups, phosphorus has one lone pair electron group, and chlorine has three lone pair electron groups.

     

    1. Draw the Lewis structure for each substance. Double or triple bonds may be needed.
      1. SiO2
      2. C2H4 (assume two central atoms)
    Answer
    1. Linear structure of silicon dioxide showing two covalent bonds connecting each oxygen to the central silicon. Each oxygen has two lone pair electron groups and silicon has zero lone pair electron groups.
    2. Chemical structure of ethylene showing two covalent bonds connecting the central carbons. Two separate covalent bonds connect two hydrogens to each carbon. There are no lone pair electron groups.

     

    1. Write the Lewis structure for the diatomic molecule P2, an unstable form of phosphorus found in high-temperature phosphorus vapor.
    Answer

    Linear structure of phosphorus (P2) showing three covalent bonds connecting the phosphorus atoms. There is a single lone pair electron group on each phosphorus.

     

    1. Write Lewis structures for the following:
      1. H2
      2. HBr
      3. PCl3
      4. HNNH
      5. H2CNH
    Answer
    1. Linear structure of hydrogen showing a single covalent bond connecting the hydrogen atoms. There are no lone pair electron groups.
    2. Linear structure of hydrogen bromide showing a single covalent bond connecting hydrogen to bromide. There are three lone pair electron groups on bromine and zero lone pair electron groups on hydrogen.
    3. T-shaped chemical structure of phosphorus trichloride showing a single covalent bond connecting each chlorine to phosphorus. Phosphorus has a single lone pair electron group and each chlorine has three lone pair electron groups.
    4. Chemical structure of HNNH showing two separate covalent bonds connecting each hydrogen to a nitrogen. The nitrogens are connected by two covalent bonds. Each nitrogen has a single lone pair electron group.
    5. Chemical structure of CH2NH showing two hydrogens connected to carbon by two separate covalent bonds. Another hydrogen is connected to nitrogen by a single covalent bond. Two covalent bonds connect nitrogen and carbon. There is a single lone pair electron group on nitrogen.

     

    1. Write Lewis structures for the following:
      1. O2
      2. H2CO
      3. ClNO
      4. SiCl4
      5. ClCN
    Answer
    1. Linear chemical structure of O2 showing two covalent bonds connecting the two oxygen atoms. Each oxygen has two lone pair electron groups.
    2. Chemical structure of formaldehyde showing two separate covalent bonds connecting the two hydrogens to the central carbon. Two covalent bonds connect oxygen to carbon. There are two lone pair electron groups on oxygen.
    3. Bent chemical structure of nitrosyl chloride showing a single covalent bond connecting chlorine to the central nitrogen and two covalent bonds connecting oxygen to the central nitrogen. There is one lone pair electron group on nitrogen, two on oxygen, and three on chlorine.
    4. Chemical structure of silicon tetrachloride showing a single covalent bond connecting each chlorine to the center silicon. Each chlorine has three lone pair electron groups.
    5. Linear chemical structure of cyanogen chloride showing a single covalent bond connecting chlorine to the central carbon and three covalent bonds connecting nitrogen to carbon. A single lone pair electron group is on nitrogen and three lone pair electron groups are on chlorine.

     

    1. Carbon tetrachloride was formerly used in fire extinguishers for electrical fires. It is no longer used for this purpose because of the formation of the toxic gas phosgene, Cl2CO. Write the Lewis structures for carbon tetrachloride and phosgene.
    Answer

    CCl4: Chemical structure of carbon tetrachloride showing single covalent bonds connecting four chlorine atoms to a central carbon atom. Each chlorine has three electron lone group pairs.Cl2CO:  Chemical structure of phosgene showing two covalent bonds connecting oxygen to the central carbon. Two separate covalent bonds connect two separate chlorine atoms to the central carbon. Oxygen has two electron lone group pairs and each chlorine has three electron lone group pairs.

     

    1. The arrangement of atoms in several biologically important molecules is given here. Complete the Lewis structures of these molecules by adding multiple bonds and lone pairs. Do not add any more atoms.
      1. the amino acid serine:  A Lewis structure is shown. A nitrogen atom is single bonded to two hydrogen atoms and a carbon atom. The carbon atom is single bonded to a hydrogen atom and two other carbon atoms. One of these carbon atoms is single bonded to two hydrogen atoms and an oxygen atom. The oxygen atom is bonded to a hydrogen atom. The other carbon atom is single bonded to two oxygen atoms, one of which is bonded to a hydrogen atom.
      2. urea:  A Lewis structure is shown. A nitrogen atom is single bonded to two hydrogen atoms and a carbon atom. The carbon atom is single bonded to an oxygen atom and another nitrogen atom. That nitrogen atom is then single bonded to two hydrogen atoms.
      3. pyruvic acid:  A Lewis structure is shown. A carbon atom is single bonded to three hydrogen atoms and another carbon atom. The second carbon atom is single bonded to an oxygen atom and a third carbon atom. This carbon is then single bonded to two oxygen atoms, one of which is single bonded to a hydrogen atom.
      4. uracil:  A Lewis hexagonal ring structure is shown. From the top of the ring (moving clockwise), three carbon atoms, one nitrogen atom, a carbon atom, and a nitrogen atom are single bonded to each another. The top carbon atom is single bonded to an oxygen atom. The second and third carbons and the nitrogen atom are each single bonded to a hydrogen atom. The next carbon atom is single bonded to an oxygen atom, and the last nitrogen atom is single bonded to a hydrogen atom.
      5. carbonic acid:  A Lewis structure is shown. A carbon atom is single bonded to three oxygen atoms. Two of those oxygen atoms are each single bonded to a hydrogen atom.

     

    Answer
    1. A Lewis structure is shown. A nitrogen atom is single bonded to two hydrogen atoms and a carbon atom. The carbon atom is single bonded to a hydrogen atom and two other carbon atoms. One of these carbon atoms is single bonded to two hydrogen atoms and an oxygen atom. The oxygen atom is bonded to a hydrogen atom. The other carbon is single bonded to two oxygen atoms, one of which is bonded to a hydrogen atom. The oxygen atoms have two lone pairs of electron dots, and the nitrogen atom has one lone pair of electron dots.
    2. A Lewis structure is shown. A nitrogen atom is single bonded to two hydrogen atoms and a carbon atom. The carbon atom is single bonded to an oxygen atom and one nitrogen atom. That nitrogen atom is then single bonded to two hydrogen atoms. The oxygen atom has two lone pairs of electron dots, and the nitrogen atoms have one lone pair of electron dots each.
    3. A Lewis structure is shown. A carbon atom is single bonded to three hydrogen atoms and a carbon atom. The carbon atom is single bonded to an oxygen atom and a third carbon atom. This carbon is then single bonded to two oxygen atoms, one of which is single bonded to a hydrogen atom. Each oxygen atom has two lone pairs of electron dots.
    4. A Lewis hexagonal ring structure is shown. From the top of the ring, three carbon atoms, one nitrogen atom, a carbon atom and a nitrogen atom are single bonded to one another. The top carbon is single bonded to an oxygen, the second and third carbons and the nitrogen atom are each single bonded to a hydrogen atom. The next carbon is single bonded to an oxygen atom and the last nitrogen is single bonded to a hydrogen atom. The oxygen atoms have two lone pairs of electron dots, and the nitrogen atoms have one lone pair of electron dots.
    5. A Lewis structure is shown. A carbon atom is single bonded to three oxygen atoms. Two of those oxygen atoms are each single bonded to a hydrogen atom. Each oxygen atom has two lone pairs of electron dots.

     

    11.7:  Predicting the Shapes of Molecules

    1. What is the basic premise behind VSEPR?
    Answer

    Electrons groups (bonds and lone pair electrons) want to be as far from each other as possible due to the negative charges in the groups repelling each other.

     

    1. What is the difference between the electron group geometry and the molecular geometry?
    Answer

    Electron group geometry tells where all electron groups are located. Molecular geometry tells where the atoms are located.

     

    1. Identify whether the following molecules are linear or bent.
      1. H2S
      2. HCN
      3. CS2
    Answer
    1. bent 
    2. linear
    3. linear

     

    1. Identify whether the following molecules are linear or bent around the central atoms.
      1. C2Cl2 (both C atoms are central atoms and are bonded to each other)
      2. N2H2 (both N atoms are central atoms and are bonded to each other)
    Answer
    1. linear
    2. bent

     

     

    This page was adapted from "Beginning Chemistry (Ball)" by LibreTexts and is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Vicki MacMurdo (Anoka-Ramsey Community College) and Lance S. Lund (Anoka-Ramsey Community College).

    This page titled 11.10: Exercises is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Anonymous.