Hybridization of a triple bond?

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MCATMadness

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In HCN, what is the hybridization of the sigma bond bw the C and N? The answer is sp.

I don't understand "hybridization of the sigma bond"? How does this differ from hybridization of the atom... and why is the answer sp?
 
Sigma bonds are made from head-on overlap of hybrid orbitals. The other two pi bonds are made from parallel overlap of p-orbitals.
 
sp1.

The H-C=N molecular shape is linear. Triple bonds involving carbon are like that.
 
In HCN, what is the hybridization of the sigma bond bw the C and N? The answer is sp.

I don't understand "hybridization of the sigma bond"? How does this differ from hybridization of the atom... and why is the answer sp?

A triple bond is made of 1 Sigma and 2 Pi bonds;

in regards to valence bond theory (orbital mixing), we hypothetically mix

1s orbital and 3 p orbitals to get= 4 equivalent sp3 orbitals (for alkanes)
1s orbital and 2 p orbitals to get =3 equivalent sp2 orbitals (alkenes)
^the P orbital that wasn't hybridized is left over, and when it overlaps with another p orbital you get a pi bond


so, for alkynes, C-C triple bonds, the sigma bond is sp hybridized because only an 1s orbital and 1 p orbital hybridize to give 2 equivalent sp orbitals; this sp orbital makes the SIGMA bond; the two 2 orbitals that weren't hybridized give the pi bonds.

it is the UNHYBRIDIZED P orbitals that make up the Pi bonds; the hybridized p orbitals that "mix" with the s orbital make the sigma bond, and hence, for alkynes, only an S and P orbital mix so the sigma bond is sp hybridized.
 
Hybrid orbitals are used to make sigma bonds and to accommodate lone pairs also .
In HCN
carbon and nitrogen has a triple bond
Carbon is bonded with H and N both so needs only two sigma bonds which are provided by two sp orbitals
N is bonded to one C and and has a lone pair on it
it also needs two hybrid orbitals --one to form sigma bond with C and other to accommodate lone pair
hence N is also sp hybridized
 
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