hello

my teacher has really confused me.
can anyone tell me how you can figure out the shapes of molecules and what types of shapes there are???
i am really confused!
thankyou
xxxx

It is confusing and it is complicated to try to explain. The easiest way to do the simple ones is to determine the number of "regions of high electron density."

Then if there are two, linear as in HF. Three makes the molecule trigonal planar, four makes the molecule tetrahedral, five makes it trigonal bipyramidal, and six is octahedral. If you have some specific question, please post it and someone will try to address that specific one. In most freshman texts this one issue takes up about three long chapters and it gets more complicated as we try to differentiate between electronic shape and molecular shape.

thanks for your help drbob222 are you a doctor or something???????

Ph. D. in chemistry from Missouri University (a long time ago).

oooh that well cool...how long was your degree for then???

Hello! I'd be happy to help you understand how to determine the shapes of molecules and the different types of shapes.

To determine the shape of a molecule, you need to consider its electron geometry and molecular geometry. Here's how you can figure it out:

1. Determine the electron geometry: Start by counting the number of electron groups (bonding pairs and lone pairs) around the central atom. Electron groups repel each other and try to get as far apart as possible, forming specific arrangements.

2. Identify the molecular geometry: Once you know the electron geometry, you can identify the molecular geometry by considering ONLY the positions of the bonding pairs. You ignore the lone pairs for this step.

Now, let's discuss the different types of molecular shapes:

1. Linear: There are two electron groups around the central atom, arranged in a straight line. For example, carbon dioxide (CO2) has a linear shape.

2. Trigonal planar: There are three electron groups around the central atom, forming a flat triangular shape. For example, boron trifluoride (BF3) has a trigonal planar shape.

3. Tetrahedral: There are four electron groups around the central atom, forming a 3D shape resembling a pyramid. For example, methane (CH4) has a tetrahedral shape.

4. Trigonal pyramidal: There are three electron groups around the central atom, with one lone pair. This results in a pyramid-like shape. For example, ammonia (NH3) has a trigonal pyramidal shape.

5. Bent: There are two electron groups around the central atom, with two lone pairs. This leads to a bent or V-shaped molecular geometry. For example, water (H2O) has a bent shape.

6. Trigonal bipyramidal: There are five electron groups around the central atom, resulting in a three-atom axial plane and two-atom equatorial plane. For example, phosphorus pentachloride (PCl5) has a trigonal bipyramidal shape.

7. Octahedral: There are six electron groups around the central atom. This leads to a shape resembling two square pyramids, sharing their base. For example, sulfur hexafluoride (SF6) has an octahedral shape.

Remember that lone pairs affect the shape of the molecule, so don't forget to consider them while determining the shape.

I hope this explanation helps you understand how to figure out the shapes of molecules and the types of shapes they can have. Let me know if you have any further questions!