Lewis Dot Structure Notes

 

Part I: For each of the following elements, draw a dot representing each valence electron around the chemical symbol (this is called a Lewis Dot Structure), then answer the questions:

 

                          C                N                O                F                 Ne

                  

                          Si                P                 S                 Cl                Ar

 

 

Part II:  How do these elements come together in a bond?

BOND

• A chemical bond is two valence electrons holding together two atoms.
• Electrons tend to attract the opposite nucleus causing the atoms to stick together.

 

 

LEWIS DOT STRUCTURES

• Symbols that represent atoms, their valence electrons and how they connect in a bond.

       _**

Ex.           H  :  O   :  H 

                  ^**

Shows water with two hydrogens sharing an electron each with oxygen.  Notice that oxygen is shown with all 6 valence electrons.

 

• Rules for drawing Lewis Dot Structures of an element.

1. Write the symbol for the element.
2. Write one dot for each valence electron around the symbol.
• Each dot must line up with a side (think 3, 6, 9, 12 on a clock)
• If more than 4 electrons are needed, the last electrons must pair up with another.
• Paired electrons do not bond.  Unpaired electrons bond.

See drawings on the board, this is beyond my computer skills.

 

• Rules for Lewis Dot Structures showing bonds.

1. Begin with the Dot Structure of the element that has the most possible bonds (unpaired electrons).  If there is more than 1 of that element, make a chain.
2. Add the element with the next most bonds making sure that the unpaired electrons line up in a bond.  (You may arrange the paired and unpaired electrons on any side that makes the drawing easy.)
3. Continue adding atoms until all unpaired electrons are used in bonds and all atoms from the compound are used up.

(You will often find many possible arrangements of atoms, that is OK.)

Again this will make sense when I draw it on the board.

 

Bonding Notes

OCTET RULE

1. Atoms bond until their valence electrons look like the nearest noble gas.
2. For all atoms above carbon, that is 8 valence electrons.
3. We call this the “octet rule”.

 

MULTIPLE BONDS

1. For some molecules, more than two electrons must be shared. 
2. We share multiples of two and call them double or  triple bonds.

 

Ex.  Draw the Lewis Dot Structure for Carbon Dioxide.

          See the board again.

Ex. Draw the Lewis dot structure for Nitrogen gas (N₂).

          Yep, See the board.

 

“HONC 1234” RULE

If you notice, Hydrogen bonds once, oxygen bonds twice, Nitrogen bonds 3 times, and Carbon bonds 4 times.  Saying “HONC 1234” helps you remember these numbers.

 

 

 

Lewis Dot Structure Notes

 

Part I: For each of the following elements, draw a dot representing each valence electron around the chemical symbol (this is called a Lewis Dot Structure).

 

                          C                N                O                F                 Ne

                  

                          Si                P                 S                 Cl                Ar

 

 

Part II:  How do these elements come together in a bond?

BOND

• A chemical bond is:
• Why do atoms stick together?

 

 

LEWIS DOT STRUCTURES

• What are Lewis Dot Structures?

 

Ex.

 

Shows water with two hydrogens sharing an electron each with oxygen.  Notice that oxygen is shown with all 6 valence electrons.

 

• Rules for drawing Lewis Dot Structures of an element.

1.  

2.  

• Each dot must
• If more than 4 electrons are needed,

 

• Paired electrons…
• Unpaired electrons…

See drawings on the board, this is beyond my computer skills.

 

• Rules for Lewis Dot Structures showing bonds.

1.  

 

 

 

2.  

 

 

3.  

 

4.

 

Again this will make sense when I draw it on the board.

 

Bonding Notes

OCTET RULE

1.         

2.  

 

MULTIPLE BONDS

1.   For some molecules, more than two electrons must be shared. 

2.   We share multiples of two and call them double or  triple bonds.

 

Ex.  Draw the Lewis Dot Structure for Carbon Dioxide.

          See the board again.

Ex. Draw the Lewis dot structure for Nitrogen gas (N₂).

          Yep, See the board.

 

“HONC 1234” RULE

 

Please memorize all these rules.  They will make many ideas next semester easier.

 

Homework:

1. Write the definition of a bond and all the Rules on these notes 10x.

2. Create 10 compounds by taking one metal and one non-metal or two non-metals and creating Lewis Dot Structures for that combination of elements.  Be sure to use the octet rule to determine the number of each element required.