IB Docs (2) Team MC test: Hybridization
Multiple choice test on 14.2 Hybridization
Use the following 'quiz' to test your knowledge and understanding of this sub-topic. You will need access to a periodic table (Section 6 of the IB data booklet).
If you get an answer wrong, read through the explanation carefully to learn from your mistakes.
Fipronil is an insecticide with the following structure
What is the hybridization on the carbon atoms labelled x, y and z?
The carbon atom labelled z is in the benzene ring so is sp2, −CF3 has four single bonds surrounding the carbon atom so y is sp3 and −CN is a triple bond so x is sp.
Which row contains the correct hybridization for the central atom in molecules with the stated shape?
| Row | Trigonal planar | Linear | Tetrahedral |
| 1 | sp | sp2 | sp3 |
| 2 | sp3 | sp | sp2 |
| 3 | sp2 | sp | sp3 |
| 4 | sp2 | sp3 | sp |
The correct shape associated with each type of hybridization can deduced from repulsion theory. Two hybrid orbitals - linear, three hybrid orbitals - trigonal planar and four hybrid orbitals - tetrahedral.
Which combination of atomic orbitals will form σ bonds?
I. sp3 and sp3
II. s and sp2
III. sp2 and sp3
They all do as π bonds will only be formed when two p orbitals combine 'sideways on'.
What are the correct numbers and types of hybridized carbon atoms in aspirin?
The carbon atoms in the benzene ring and the two carbonyl carbon atoms are all sp2 hybridized. Only the methyl carbon atom is sp3 hybridized.
Which statements are correct when a free carbon atom becomes sp2 hybridized?
I. One of the 2s electrons is promoted to a 2p orbital, two of the 2p orbitals then hybridize with the remaining 2s orbital.
II. The three sp2 orbitals and the remaining p orbital are equal in energy.
III. Each one of the sp2 orbitals contains one electron from the carbon atom.
The 2p sub-level is higher in energy than the 2s sub-level. When the s orbital hybridizes with two of the 2p orbitals the new hybrid sp2 orbital will be between the s and p sub-levels in energy but the remaining p orbital will still be in the higher p sub-level.
When bromine adds to ethene to form 1,2-dibromoethane what will happen to the hybridization on the carbon atom?
C2H4 + Br2 → C2H4Br2
The C=C double bond is broken and a C−C single bond is formed so it changes from sp2 to sp3.
How many carbon atoms in heroin are sp2 hybridized?
The aromatic ring contains six, there are two carbonyl groups, C=O and one C=C double bond in one of the other rings giving a total of ten sp2 hybridized carbon atoms.
In which species are the nitrogen atoms hybridized in the order: sp, sp2 and sp3?
HCN is a linear molecule so the N must be sp hybridized. In the nitrate ion N has three electron domains around it making it trigonal planar so the N must be sp2 hybridized. NH3 has four electron domains around the N atom (three bonding pairs and one non-bonding pair of electrons) so it must be sp3 hybridized.
Which describes the hybridization in carbon monoxide, CO?
There is a triple bond between the C and O atom and both C and O contain one non-bonding pair of electrons. From this it can be deduced that the hybridization is sp. One of the sp orbitals overlaps to form a σ bond between C and O and the non-bonding pair on each atom are located in the other sp hybridized orbital. The remaining two bonds in the triple bond between C and O are both π bonds formed by the overlap of p orbitals.
Which species contain a central atom which is sp3 hybridized?
From VSEPR theory the only one that is tetrahedral in shape with bond angles close to 109o is PCl3. ICl4+ has six electron domains around the central atom making it seesaw shape and XeF4 has six electron domains around the Xe atom making it square planar. CO32- has three electron domains giving a bond angle of 120o so the C atom in CO32− is sp2 hybridized.
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