13 posts • Page 1 of 1
Something to keep in mind as well is when lone pairs are involved it changes the bond angle from the expected amount. For example NH3 has bond angles of 107 degrees instead of the expected 109.5 degrees. There is no way to know this since it needs to be tested in the lab since it's unique to each molecule so we represent the cases with lone pairs as saying that the bond angle is less than 109.5 degrees.
Drawing out the shape of the molecule helps to see where each bond is located and therefore where each bond angle would be. It would be a lot harder to determine bond angles without actually drawing out the shape through VSEPR
If you know the VSEPR model , you should be able to remember the bond angle associated with it like 120, or 109.5, or 90 degrees. Then figure out how the lone pairs push on the bonding pairs and affect the angles ( I find this is easiest by drawing it).
I assume that for the next exam/final, we will only be asked to determine the bond angles when also asked to draw the Lewis Structure for partial points. So, you'd draw the dot structure then determine the VSEPR shape and corresponding bond angles. Finding the dot structure is really important because it tells you the written shape of the molecule/ which atoms are connected + lone pairs, so I would suggest practicing that so it makes the process faster.
Who is online
Users browsing this forum: No registered users and 2 guests