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CHE 105/110 Introduction to Chemistry - Exercises and Answers

Covalent Bonds

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QUESTION ANSWER

1.

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

1.

two

3.

What is the Lewis electron dot diagram of I2? Circle the electrons around each atom to verify that each valence shell is filled.

3.

 

A Lewis structure of Iodine molecule shows one pair of shared electrons by both atoms (covalent bond). The lone pairs of electrons on individual atoms that are not part of the covalent bond are also shown. The Iodine molecule (I2) has one single covalent bond formed by two valence electrons, one from each Iodine atom.

5.

What is the Lewis electron dot diagram of NCl3? Circle the electrons around each atom to verify that each valence shell is filled.

5.

A Lewis structure of NCl3 (Nitrogen Trichloride) molecule shows pairs of shared electrons that form three single covalent bonds between Chlorine and Nitrogen. The lone pairs of electrons on individual atoms that are not part of the covalent bonds are also shown. The NCl3 (Nitrogen Trichloride)  molecule has three single covalent bonds, each one formed by one valence electron from Chlorine atom and one valence electron from Nitrogen.

7.

Draw the Lewis electron dot diagram for each substance.

  1. SF2
  2. BH4

7.

  1.  

    A Lewis structure of SF2 (Sulfur Difluoride) molecule shows two pairs of shared electrons (covalent bond) forming two single covalent bonds between Sulfur and Fluorine. The figure also shows the lone pairs of electrons on individual atoms that are not part of the covalent bonds. The SF2 (Sulfur Difluoride)  molecule has two single covalent bonds, each one formed by one valence electron from Fluorine atom and one valence electron from Sulfur.
  2.  

    Single covalent bonds between Hydrogen (H) and Boron in the Tetraborohydride ion (BH4-) are shown by lines.

9.

Draw the Lewis electron dot diagram for each substance.

  1. GeH4
  2. ClF

9.

  1.  

    Single covalent bonds are shown by single lines between Hydrogen (H) and Germanium (Ge) in the Germanium (IV) Hydride.
  2.  

    A single covalent bond is shown by two dots between both atoms in the Chlorine Fluoride molecule. The other dot pairs are the lone pairs of electrons.

11.

Draw the Lewis electron dot diagram for each substance. Double or triple bonds may be needed.

  1. SiO2
  2. C2H4 (assume two central atoms)

11.

  1.  

    The Silicon Dioxide (SiO2) molecule shows two pairs of double covalent bonds (doble lines) between Silicon and each Oxygen. Each Oxygen atom shares two electrons with Silicon. The Silicon atom shares four electrons, two with each Oxygen. The molecule structure also shows two lone pairs of electrons on each oxygen atom.
  2.  

    The Ethene molecule (organic compound) shows a double covalent bond (double line) between both Carbon atoms. Each carbon forms two single covalent bonds represented by single lines with Hydrogen.

13.

Draw the Lewis electron dot diagram for each substance. Double or triple bonds may be needed.

  1. CS2
  2. NH2CONH2 (assume that the N and C atoms are the central atoms)

13.

  1.  

    The Carbon Disulfide (CS2) molecule shows two pairs of double covalent bonds (doble lines) between Carbon and each Sulfur. Each Sulfur atom shares two electrons with Carbon. The Carbon atom shares four electrons, two ones with each Sulfur. The molecule structure also shows two lone pairs of electrons on each Sulfur atom.
  2.  

    The organic compound molecule structure shows single covalent bonds (single lines) between Hydrogen and Nitrogen, and between Nitrogen and Carbon. It is also shown a double covalent bond (double line) between Carbon and Oxygen and lone pairs of electrons on Oxygen and Nitrogen.

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