1.1 What is Chemistry?

http://www.ck12.org Chapter 9. Covalent Bonding

2. Draw each atom by using its element symbol. The number of valence electrons is shown by placing up to two
   dots on each side of the element symbol, with each dot representing a single valence electron.


3. Predict the number of covalent bonds each atom will make using the octet rule.


4. Draw the bonding atoms next to each other, showing a single covalent bond as either a pair of dots or a line
   representing a shared valence electron pair. If the molecule forms a double or triple bond, use two or three
   lines to represent the shared electron pairs, respectively.

Lesson Summary

• Covalent bonds are formed between atoms sharing electrons.


• Lewis structures are a simple way of representing covalent bonds. The shared valence electrons can be drawn
  using dots to represent individual valence electrons, or lines to represent shared electron pairs.


• A pair of valence electrons in a bonded atom that does not participate in bonding is called a lone pair. Lone
  pair electrons contribute to molecular shape.


• Atoms can form double or triple covalent bonds as well, in which each atom shares two valence electrons
  (double bond) or three valence electrons (triple bond).

Lesson Review Questions

1. How is a covalent bond formed?


2. What is the major difference between a covalent bond and an ionic bond?


3. What orbitals are used in covalent bonding?


4. What types of elements generally form covalent bonds?


5. How do double and triple covalent bonds differ from single covalent bonds?


6. Predict the number of covalent bonds the following atoms will make:
   a. N (nitrogen)
   b. S (sulfur)
   c. Br (bromine)
   d. F (fluorine)


7. Draw Lewis structures for the following molecules:
   a. HBr
   b. CO 2
   c. NCl 3
   d. PCl 5


8. Determine how many lone pairs are present in each of the molecules from the problem above.

Further Reading / Supplemental Links

• An extensive collection of materials showing the contributions made by Linus Pauling to our understanding
  of the chemical bond: http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/


• Practice drawing Lewis Dot Structures of Covalent Compounds: http://www.wisc-online.com/objects/ViewO
  bject.aspx?ID=GCH6404