Video Transcript
Atomic orbitals in the second quantum number of a carbon atom hybridize to form sp3
hybrid orbitals. Which statement correctly describes the energy level of the resulting sp3 hybrid
orbitals? (A) The sp3 hybrid orbitals are at the same energy level as the original 2p
orbitals. (B) The sp3 hybrid orbitals are at the same energy level as the original 2s
orbital. (C) The sp3 hybrid orbitals are at a higher energy level than the original 2p
orbitals. (D) The sp3 hybrid orbitals are at a lower energy level than the original 2s
orbital. (E) The sp3 hybrid orbitals are at an energy level in between the original 2s orbital
and the 2p orbitals.
In this question, we are asked to describe the energy level of the sp3 hybrid
orbitals in a hybridized carbon atom in relation to the atomic orbitals in an
unhybridized carbon atom. When referring to orbitals in a quantum number, it is the principal quantum number
that is implied. So here, 𝑛 equals two. This is this second energy level of a carbon atom. Let’s clear some space to see this visually.
A carbon atom has atomic number Z of six. This tells us that an atom of carbon has six protons in its nucleus. Since the number of protons is equal to the number of electrons in a neutral atom,
there are six electrons in a carbon atom. These six electrons are arranged into the different energy levels, or quantum
numbers, as follows.
In the first shell or quantum number, there are two electrons. And in the second shell or quantum number, there are four electrons. The two electrons in the first shell have the lowest energy. Specifically, they are found in an s orbital. s orbitals are spherical in shape. The four electrons in the second energy level, or second quantum number, are
distributed between the 2s orbital and the 2p orbitals. The 2s orbital is lower in energy than the 2p orbitals. The 2s orbital contains two electrons, and this orbital is spherical in shape. The remaining two electrons are unpaired and are found in two of the 2p orbitals,
which are dumbbell in shape. p-type orbitals are complex dumbbell shapes, which are
plane-polarized, each around one of the three Cartesian coordinate axes.
It would be reasonable to suggest that the 2s and 2p orbitals interact differently
when bonding with other atoms. But this is not the case at all. What happens is one of the 2s electrons is promoted to a 2p orbital. Then, these four orbitals, the 2s orbital and the three 2p orbitals, mix. We say the orbitals hybridize.
Hybridization is the mixing of atomic orbitals to form new hybrid orbitals, which can
then undergo electron pairing during chemical bond formation. The mixing of an s orbital with three p orbitals forms four equivalent sp3
orbitals. These hybrid orbitals all have the same shape and energy. And their energy level is somewhere between the energies of the atomic 2s orbital and
the atomic 2p orbitals which they came from.
We were asked to compare the energy of the sp3 hybrid orbitals with the atomic
orbitals they came from. Let’s bring back our answers. So, we can deduce that the statement correctly describing the energy level of the
resulting sp3 hybrid orbitals is (E). The sp3 hybrid orbitals are at an energy level in between the original 2s orbital and
the 2p orbitals.
