Chemical Bonding

(9 Days)

 

Labs: Relative Solubilities, "Bond It" Activity

Supplemental Problems:

1) What energy condition do you think must exist if a chemical bond is to form between two approaching atoms? Would the energy possessed by the individual atoms be greater or smaller than the energy possessed by the bonded atoms?

2) The ionic solid, LiF is formed when Li loses an electron to become Li ⁺¹ and F gains that electron to become F ^-1.

a) Draw energy diagrams of Li and Li +1to show the loss of an electron.

b) Draw energy diagrams of F and F -1to show the gain of an electron.

c) Use electron configurations to show how Li loses an electron.

d) Use electron configurations to show how F gains an electron

e) Use an electron dot picture to show the loss of an electron by Li.

f) Use an electron dot picture to show the gain of an electron by F.

3) CaF₂ is an ionic solid that forms from the Ca ²⁺ ion and 2 F ^-1 ions. Repeat a) -f) in question 2 for CaF₂.

4) Draw energy diagrams and electron dot representations to show the covalent bonding in Cl₂O, HCl, and Cl₂.

5) Draw an electron dot diagram of CH₃Cl.

6) Draw an electron dot diagram of PF₂H.

7) Use your answers to problem 4 to draw a 3-D drawing of the three molecules in question 4.

8) Use an energy diagram and electron dot diagram to show how beryllium can hybridize so that it can form two bonds. Repeat this for boron (so it can make 3 bonds) and carbon (4 bonds).

9) Draw energy diagrams, electron dot representations, and structural formulas for the following molecules:

a) BeF₂ (it does not contain 8 e- around Be)
b) BH₃ (it does not contain 8 e- around B)
c) H₂O₂
d) H₂S₃

10) Draw an energy diagram, electron dot representation, and 3-D drawing of a water molecule. What do you notice about the shape of a water molecule?

11) Draw formula, electron dot, and structural representations of carbon monoxide and carbon dioxide. (You will have to use double or triple bonds.)

12) Repeat problem 2) for a nitrogen gas molecule.

13) Draw electron dot and structural formulas of the molecule N₂H₄, hydrazine. Hydrazine is used as rocket fuel and is highly toxic. Much effort is currently directed at cleaning up hydrazine spills at rocket research facilities in Seattle, California, and Cape Canaveral.

14) See if you can draw an electron dot picture and a structural formula for the cyanide ion (CN^-).

15) Draw electron dot formulas for the molecules CH₃Cl, CH₂Cl₂, CHCl_3, and CCl₄.

16) Show a possible bonding arrangement for cyclobutane, C₄H₈, in which the four carbon atoms are in a ring. Use a dash for each bond.

17) Ethylene is the first of a family of hydrocarbons called alkenes. Each alkene has one double bond in the structure, Use line drawings to show bonding in the compounds ethylene, C₂H₄, and propylene, C₃H₆.

18) Acetylene is the first of a family of hydrocarbons called alkynes. Each alkyne has one triple bond in the structure. Use line drawings to show bonding in the compounds acetylene, C₂H₂, and propyne, C₃H₄.

19) Which of these molecules would you expect to be hydrogen-bonded in the liquid or solid state?

(a) H3COH

(b) H3CH

(c) Cl3CH

(d) H3CNH2

(e) H2NNH2

20) Is liquid ammonia (NH3) hydrogen-bonded? What evidence do you have for your answer? 22) Use hydrogen bonding to suggest why ethanol (CH3CH2OH) is soluble in any proportion in H2O, formaldehyde (H2C=O) , and dimethyl ether (CH3-O-CH3), but is hardly soluble in octane (C8H18).   23) Describe the properties molecules must have for hydrogen bonding to occur. 24) Use the graph at right to estimate the boiling temperature of H2O, HF, and NH3 if H-Bonding did not occur.

  

 

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