and Bonding: Discovering Resonance
Draw the Lewis dot structure of the carbonate ion,
CO3-2. Remember to add two electrons for the charge
on the ion.
Is there any reason why the double bond in the
carbonate ion cannot be located at one of the other oxygens?
From a statistical point of view, the double bond
has a 0.33 chance (1 out of 3) to be located at any one of the oxygens. So
you have three possible structures for the carbonate ion. These are called
At any time, can we isolate and find a double
bond? Here is the structure of the carbonate ion.
Measure the carbon-to-oxygen bond lengths (right click, click on select, then mouse click
action, then click on distance). Consecutively click on the two atoms in
the bond. Distance is shown on the lower left corner of your browser
screen. For the distance in picometers (pm): pm = distance x 100. Explain what you find.
What happened to the double bond? Measure
and record in picometers the carbon-to-oxygen bond lengths in the three molecules given below,
which illustrate the three different bond orders (BO).
BO = 3
BO = 2
BO = 1