CH2CHCN geometry

[Chem_Mod]

Question: on number 25 in chapter 3, how do we know that the 2H in (CH2) is bonded at an angle of 120 degrees? I initially drew it as linear, but the solution manual says the angle is actually 120 degrees.

[Chem_Mod]

Answer: In 3.25, we have to draw CH2CHCN. That has 3 segments - CH2, connected to CH connected to CN. The CH2 will need two more bonds, CH three more bonds and CN one more bond. If we connect CH to CN, we still need two more bonds to the CH. That suggests we have a double bond between the CH2 and CH. The C in CH2 then has 3 regions of electron density (two bonds to H and one double bond to C) and we use a trigonal planar geometry with 120 degree angles.

[Dang Lam]

Is there a different way to draw this structure or that is the only one. Also I noticed that the way the formula is written matched with the drawing so is that like a hint on how to draw a lewis structure for a molecule?

[Marcela Udave 1F]

So for this problem we don't describe the hybrid orbitals on each carbon atom? Or by describing the CH2 we identify the hybrid orbital of Acrylonitrile?