Shapes of molecules

at are the 3 symbols for drawing shapes of 3d molecules and what do they mean?

• A straight line - The bond is in the 2 plane of vision

• A dotted line/wedge - The bond is moving away from you

• A coloured wedge - The bond is moving towards you

What are the 5 shapes of molecules that have no lone pairs and how many bond pairs do each have ?

• Linear - 2 bond pairs

• Trigonal planar - 3 Bond pairs

• Tetrahedral - 4 bond pairs

• Trigonal Bipyramidal - 5 Bond pairs

• Octahedral - 6 lone pairs

What is the bond angle(s) of a linear molecule and what is an example?

• 180 degrees

• CO2

What is the bond angle(s) of a trigonal planar molecule and what is an example?

• 120 degrees

• AlCl3

What is the bond angle(s) of a tetrahedral molecule and what is an example?

• 109.5 degrees

• CH4

What is the bond angle(s) of a trigonal bipyramidal molecule and what is an example?

• The bonds which are in the 2d-plane have a 90 degree angle bond

• The bonds which are moving towards you and away from you are 120

• PCl5

What is the bond angle(s) of a octahedral molecule and what is an example?

• All bonds are 90 degrees to each other

• SF6

What are the 3 steps to predicting the shape of a covalent molecule?

1. Draw the dot and cross diagram

2. Count how many bond pars and lone pairs there are

3. Work out the shape based of the number of bond pairs and lone pairs that there are

What are 2 shapes of molecules which have lone pairs, how many bond pairs and lone pairs do they have

• Trigonal Pyramidal - 3 bond pairs, 1 lone pair

• Non-linear - 2 bond pairs, 2 lone pairs

What is the bond angle of trigonal pyramidal and what is an example?

• 107 degrees

• NH3

What is the bond angle of a non-linear molecule and what is an example?

• 104.5 degrees

• H2O

How many degrees do you subtract of the bond angle for every lone pair that you have?

• -2.5 degrees for every lone pair