Why is there not an sp4 hybrid orbital?

Answer 1

Because there exist exactly three #p# orbitals per quantum level #n#, and because the #(n-1)d# orbital is closer in energy to the #(n-1)s# orbital than an #np# orbital.

It sounds like a misunderstanding of the hybridization notation.

HYBRIDIZATION NOTATION

Having #sp^3# hybridization tells you that one #ns# orbital mixes with three #np# orbitals to generate four identical (in symmetry), degenerate (in energy) #sp^3# orbitals. That way, the given compound can form up to four identical bonds if it wishes.

From the explanation above, using #n = 4#, it follows that #sp^4# implies the existence of a fourth #(n-1)p# orbital, or implies an #np# orbital somehow participates as the fourth #p# orbital.

However, that is not reasonable, given that an #np# orbital is too far away in energy to interact in place of using the #(n-1)d# orbital for #n = 4#. Furthermore, there exist only three #(n-1)p# orbitals, not four---remember that for #l = 1# (for all #p# orbitals), #m_l = {-1,0,+1}#.

A MORE EXPLICIT EXAMPLE

The #3d# orbital, for instance, is closer in energy to the #3s# orbital than the #4p# is to the #3s# for a given atom.

That means it is more favorable to mix one #3s#, three #3p#, and one #3d# if the compound wishes to form five bonds using #sp^3d# hybridization.

An example of #sp^3d# would be #PF_5#.

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Answer 2

Theoretically, sp4 hybridization would require mixing one s orbital with four p orbitals, resulting in five hybrid orbitals, which is not energetically favorable. In sp3 hybridization, one s orbital mixes with three p orbitals to form four sp3 hybrid orbitals, which are more stable.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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