How do I determine whether a carbon/molecule is either Sp, Sp1, Sp2 or Sp3?

Answer 1

sp, sp, and sp3 all have to do with how many electrons the carbon is sharing with another atom. You have to take each bond individually - not the carbon as a whole.

for example take H - C(=0) - H formaldehyde

what are the sp's of the carbon?

if you look at the C-H bond they are sp3 bonds (single bonds)

if you look at the C=O it's a sp2 bond (double bond) - one sigma bond between C and O and a pi bond between C and O.

in general:
single bond = sp3
double bond = sp2
triple bond = sp

Answer 2

First of all, sp1 is typically indicated as simply sp.

Please note that a carbon with sp3 is basically one capable of bonding with 4 other atoms forming 4 single sigma bonds. A carbon with sp2 is capable of bonding with 3 other atoms forming 3 sigma bonds and a pi bond. This means that the carbon will have a double bond: one sigma and one pi bond. A carbon with sp is capable of bonding with 2 other atoms forming 2 sigma bonds and and 2 pi bonds.

To illustrate this, let us consider ethane CH3 -CH3 or H3C-CH3. Either carbon is attached to 3 hydrogens and another carbon or a total of 4 sigma bonds, thus sp3.

The compound ethylene which is CH2=CH2 or H2C=CH2 has a carbon attached to 2 hydrogens and one carbon which makes it sp2. The other bond in the middle is the pi bond.

The compound acetylene is CH ≡ CH or H-C≡C-H has a carbon attached to one hydrogen and to another carbon which makes it sp. The two other bonds in the middle are 2 pi bonds.

Thus, a simple way to determine the hybridization is look for how many atoms are connected to the carbon. And if you see a triple bond, then it is sp; if you see a double bond, then it is sp2, else sp3.

Answer 3

sp is usually 1 triple bond and 1 single bond or 2 double bonds
sp2 is usually 1 double bond, 2 single bonds
sp3 is usually four single bonds
sp and sp1 are the same