Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: deathracer26 on November 14, 2014, 10:06:56 AM
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Does P in PH3 hybridizes like N in NH3 .
I think it doesn't hybridizes due to low electronegativity of Hydrogen . Due to this there is no partial positive charge on P causing the orbitals to contract , the 3s and 3p orbital have so much energy difference that hybridization between 3s and 3p is not energetically favourable.
I am not sure about the energy difference gap reason .
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Hydrocarbons, ammonia, and water all hybridize; therefore, I don't believe you have hit upon the correct explanation by invoking the electronegativity of hydrogen. IIRC the bond angles in PH3 are close to 94°. A previous thread here: http://www.chemicalforums.com/index.php?topic=40736.0
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Broadly speaking the hybridization scheme is similar between ammonia and phosphane. However phosophorous is a bigger, more diffuse atom than nitrogen. Because the bonds surrounding nitrogen are closer together, they exhibit more repulsion between each other, which increases the bond angles. In phosphorous, the bonds are naturally farther apart and so the bond angle can be shrunk in order to reduce interactions with the lone pair. In phosphorous the lone pair can be described as being located in a more "pure" unhybridized atomic orbital. But this is a spectrum of possibilities, not an "either/or" proposition. Some degree of hybridization can be invoked in both cases to explain the structure.
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IIRC the bond angles in PH3 are close to 94°.
which determines hybridization. NOT the other way around.
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In PH3 the H-P-H ange is ~93°
100% sp3 hybridization suggests tetrahedral 109.5° angle
Non-hybridized p-orbitals have the angle of 90°
So you can conclude that there is a very small degree of hybridization, or no hybridization at all in PH3 molecule according to the experimentally observed angles.