Chem 1711 Chapter 5 homework spc
Which of the following statements about hybridization are true?
- Hybrid orbitals within the same atom have the same energy and shape. - Hybrid orbitals are described mathematically as a linear combination of atomic orbitals. - An atom can have both hybridized and unhybridized orbitals at the same time. - Hybridization is a model used to describe the observed bonding in molecules. These hybrid orbitals are described mathematically by a process called LCAO, or the linear combination of atomic orbitals. The hybrid orbitals are equal in size, shape, and energy. sp and sp2 hybridization mixes 1 or 2 p orbitals with the s orbitals, while the remaining p orbital(s) do not form hybrid orbitals.
In a sigma bond, the electron density is concentrated:
on the internuclear axis itself - In a sigma bond, the electron density is located immediately upon the internuclear axis.
In the structure illustrating the bonding in ethene, C2H4, the two arrows point to what type of bond or bonds?
one π-bond with one lobe above and one lobe below the plane of the molecule - The π-bond is formed by the side-by-side overlap of the two unhybridized p orbitals in the two carbon atoms of ethene. The two lobes of the π-bond are above and below the plane of the molecule.
hybrid orbitals
orbitals of equal energy produced by the combination of two or more orbitals on the same atom
The diagram shows energy levels for the unhybridized atomic orbitals for the carbon atom, as well as a set of orbitals for carbon in a molecule. The two orbitals enclosed in the dashed circle are what type of orbitals?
p orbitals - The upper two, circled orbitals have energies that are the same as the atomic p orbitals, making them unhybridized p orbitals. Also note that the lower two orbitals have energies that are intermediate between the atomic s and p orbitals, making them hybrid orbitals. Because there are two hybrids, they must correspond to two equivalent sp orbitals, which will leave two p orbitals unhybridized.
A pi bond involves:
side-by-side, or lateral orbital overlap with the electron density concentrated on opposite sides of the internuclear axis. - π bonds involve side-by-side or lateral orbital overlap, in which the electron density is on either side of the internuclear axis. Along the axis itself, there is a node: a plane in which there is no probability of finding an electron.
A _______ bond is a covalent bond where the electron density is concentrated in the region along the internuclear axis.
sigma - Sigma bonds are characterized by the electron density that is concentrated along the internuclear axis (an imaginary line that would pass through the center of the overlap region). By contrast, pi bonds are formed on opposite sides of the internuclear axis.
What type of bond is formed by the direct overlap of hybrid orbitals?
sigma bonds - Recall that the direct overlap of hybrid orbitals forms σ bonds, and that the lateral overlap of unhybridized orbitals form a π bonds.
Hybridization predicts geometry best for:
small atoms - Hybridization begins to break down in its ability to predict geometry as atoms get larger.
Hybridization works best for:
small atoms - Hybridization begins to break down in its ability to predict geometry as atoms get larger.
The diagram shows energy levels for the unhybridized atomic orbitals for the carbon atom, as well as a set of orbitals for carbon in a molecule. The three orbitals enclosed in the dashed circle are what type of orbitals?
sp2 hybrid orbitals - The lower three circled orbitals have energies that are intermediate between the atomic s and p orbitals, making them hybrid orbitals. Because there are three hybrids, they must correspond to three equivalent sp2 orbitals.
Which of the following determines the strength of a covalent bond?
the amount of overlap for the orbitals involved - When overlap occurs between two atomic orbitals, the positively charged nuclei and the negatively charged electrons for the atoms involved create a covalent bond. The more overlap that occurs between two orbitals, the stronger the attraction between the positively charged nuclei and the negatively charged electrons. Therefore, the more overlap that occurs, the stronger the covalent bond.
Which of the following helps to determine the hybridization of an atom?
the number of regions of electron density around the central atom - The number of regions of electron density around the central atom is used to determine the hybridization of an atom. Regions that are considered to be electron dense are single bonds, multiple bonds, radicals, and lone pairs, each counting as one region. The total number of these regions around a central atom can be used to determine the hybridization using VSEPR theory.
Which of the following produces sigma bonds?
the overlap of an s and p orbital the overlap of two s orbitals the end-to-end overlap of two p orbitals direct orbital overlap - A sigma bond is a covalent bond that can be formed through the overlap of two p orbitals (end-to-end), two s orbitals, or an s and a p orbital. The electron density for all of these is concentrated along the internuclear axis, allowing for a sigma bond to form.
What will be the bond angles for an sp2 hybridized atom with three identical single covalent bonds?
120 degrees - An atom that is sp2 hybridized will exhibit trigonal planar geometry, which involves 120∘ bond angles.
The double bond in H2C=CH2 consists of ______ sigma bond(s) and ______ pi bond(s).
1;1 - The double bond in H2C=CH2 consists of 1 sigma bond and 1 pi bond. Single bonds are formed by sigma bonds, but multiple bonds consist of sigma and pi bonds. Each bond consists of at least (and at most) one sigma bond and the remaining are formed by the side by side overlap of pi bon
Consider the structure of carbon dioxide. How many π bonds and σ bonds are present in this molecule?
2 sigma & 2 pi bond - The structure of carbon dioxide is O=C=O. This molecule has two carbon-oxygen double bonds. Each of these double bonds consists of one C−O σ bond and one C−O π bond. Therefore, there are 2 σ bonds and 2 π bonds.
Which of the following has the correct number of s,p, and d orbitals to describe an octahedral arrangement?
3 s, 1 p, 2 d 2 s, 1 p, 3 d 0 s, 3 p, 3 d none of the above answer: none of the above - The octahedral arrangement has one s, three p, and two d orbitals. The octahedral arrangement has six electron dense regions and is not possible for atoms in the first or second period of the periodic table
How many electron domains surround an sp3 hybridized atom?
4 - An sp3 hybridized atom is surrounded by 4 electron domains.
How many regions of electron density are there on the central atom of a molecule that displays sp3d hybridization?
5 - A molecule with a central atom that is sp3d hybridized has 5 regions of electron density, or five electron domains; 1 for the s orbital 3 for the p orbitals and 1 for the d orbital.
How many σ-bonds are there in the molecule ethene, C2H4, whose orbital structure is shown below? Use a whole number in your answer.
5 - In the ethene molecule, C2H4, there are five σ-bonds. One C−C σ-bond results from overlap of an sp2 hybrid orbital on one carbon atom with an sp2 hybrid orbital on the other carbon atom. Four bonds result from the overlap between the atoms' sp2 orbitals with s orbitals of each of the individual hydrogen atoms.
How many atomic orbitals are required to generate sp3d2 hybridized orbitals?
6 - One s orbital, three p orbitals, and two d orbitals will need to be hybridized in order to form the sp3d2 hybrid orbitals.
What will be the bond angles for an sp3d hybridized atom participating in five identical single covalent bonds?
90∘ 120∘ 180∘ all of the above answer: all the above - An sp3d hybridized atom will exhibit trigonal bipyramidal geometry, which has three different bond angles. 90∘ angles separate the axial positions from the equatorial positions, 120∘ bond angles separate the equatorial positions from each other, and 180∘ bond angle that separates axial atoms.
In order for a pi bond to form, there must be:
A lateral overlap of p-orbitals. - Any direct overlap is a sigma bond, and pi bonds are specifically the lateral overlap of unhybridized p orbitals.
Which of the following exhibits sp3 hybridization?
BH3 CH2O CCl4 answer: CCl4 - CCl4 exhibits sp3 hybridization because the carbon atom has 4 electron domains.
The diagram below shows the orbitals of a carbon atom that are hybridized to form the ethene molecule, C2H4, with five regions of orbital density labeled A, B, C, D, and E. Which of the labeled lobes of electron density will form the π-bond or bonds of ethene?
C and E - In ethene, one of the 2p orbitals remains unhybridized. It has two regions of electron density, shown in red and blue and labeled C and E in the figure. The unhybridized 2p orbital is used to form the π-bond. The 2s and two of the 2p orbitals hybridize to form the sp2 hybrid orbitals that have trigonal planar geometry. The sp2 hybrid orbitals are shown as the three equivalent orange regions of electron density labeled A, B, and D.
Which molecule has a central atom that is sp3d hybridized?
CF4 BrF3 ClF5 NH3 answer: BrF3 - With two lone pairs and three single bonds, bromine has five electron domains which will make it sp3d hybridized.
Which molecule has a central atom that is sp hybridized?
CO2 - Hybridization can be determined by the number of electron domains. Only an atom with 2 electron domains will have sp hybridization. In this case, it is the carbon atom in a carbon dioxide molecule, because carbon is bonded to 2 oxygen atoms and has 0 lone pairs of electrons. The other choices all have 2 atoms bonded to the central atom and 1 or 2 lone pair of electrons, corresponding to 3 or 4 electron domains, and sp2 or sp3 hybidization.
Which molecule has a central atom that is sp3d2 hybridized?
ClF3 SF4 PCl5 IF5 answer: IF5 The iodine atom in IF5 has six electron domains, in the form of five single bonds and one lone pair, so it will be sp3d2 hybridized. ClF3 ,SF4, and PCl5 each have five electron domains, making the central atoms sp3d hybridized.
Which of the following is an example of an sp3d hybridization?
ClF3 SF6 IF+6 PCl−6 answer: ClF3 - ClF3 is an example of sp3d hybridization that has 5 electron dense regions (3 bonding, 2 nonbonding). The other answer choices have 6 electron dense regions that would not correspond to a sp3d hybridization, but rather to a sp3d2 arrangement.
Which will be the strongest bond?
H-Cl H-Br H-I answer: H-Cl - Chlorine has a smaller atomic size than bromine and iodine, therefore it has the shortest bond. When comparing similar bonds, such as the bonds between a hydrogen atom and a halogen, shorter bonds correlate with stronger bonds, H-Cl will be the strongest bond.
Consider the following structural formula for urea. What is the hybridization of the nitrogen atoms? What is the hybridization of the carbon atom?
N: sp3, C:sp2 - Each nitrogen atom has four electron domains, making it sp3, and the carbon atom has three electron domains, making it sp2.
Which of the following molecules has a nitrogen atom with an sp2 hybridization?
NO3− HCN N2 NH3 answer: NO3 - The NO3− molecule contains a nitrogen with 3 electron regions so its hybridization is sp2.
What statement is NOT correct about σ bonding?
Rotation around single σ-bonds does not occur easily. -Rotation around single (σ) bonds occurs easily because the end-to-end orbital overlap does not depend on the relative orientation of the orbitals on each atom in the bond. Rotation around the internuclear axis does not change the extent to which the bonding orbitals overlap because the bonding electron density is symmetric about the axis. Hybrid orbitals on carbon are used to form the σ-bonds between carbon atoms and between carbon and hydrogen atoms.
Which molecule has a central atom that is sp3d hybridized?
SF4 SF6 XeF4 XeF6 answer: SF4 -With four single bonds and one lone pair, the five total electron domains make the sulfur atom sp3d hybridized.
Which molecule has a central atom that is sp3 hybridized?
SF6 CH3Cl AlCl3 PCl5 answer: CH3Cl - The carbon atom has four electron domains, so it will be sp3 hybridized.
What is the hybridization of carbon in carbon dioxide (CO2)?
SP - - The carbon atom in CO2 is surrounded by 2 regions of electron density, which become arranged in a linear electron-pair geometry. The hybridization for this linear arrangement is sp.
What is the hybridization of C in CN−?
Sp -C in CN− has an sp hybridization because of its 2 regions of electron density (1 bonding, 1 non bonding).
An atom with 3 regions of electron density has what hybridization?
Sp2 - 3 regions of electron density would result in an sp2 hybridization.
Any atom that exhibits tetrahedral electron-pair geometry will have what hybridization?
Sp3 - A tetrahedral geometry means four electron domains which will require sp3 hybridization; 1 electron for the s orbital and 3 electrons for the p orbitals
What is the hybridization of the oxygen atom in a water molecule?
Sp3 - Oxygen will be sp3 hybridized in a water molecule, because it is surrounded by four electron domains, and will thus need to hybridize all four of the orbitals in its valence shell.
A bond angle of 109.5∘ corresponds to which type of hybridization?
Sp3 -A bond angle of 109.5∘ corresponds to a tetrahedral geometry. Molecules with tetrahedral geometry generally have central atoms that are sp3 hybridized.
In the structure illustrating the bonding in acetylene, C2H2, the four arrows point to what type of bond or bonds?
The four dashed lines indicate the formation of two π-bonds that are formed from the four unhybridized p orbitals. - In the acetylene molecule, C2H2, there are two π-bonds, which is indicated by the four dashed lines in the orbital structure shown. There are two dashed lines for each of the π-bonds because each of the two unhybridized 2p orbitals on a carbon atom has two areas of electron density, one on either side of the atom, that overlap with the similar areas of electron density on the two unhybridized 2p orbitals on the other carbon atom. This makes a total of four 2p orbitals and two π-bonds.
The orbital structure of the molecule ethene, C2H4, is shown below. What do the dashed lines signify?
The two dashed lines indicate the formation of one π-bond that is formed from the two unhybridized p orbitals. - In the ethene molecule, C2H4, there is one π-bond, which is indicated by the two dashed lines in the orbital structure shown. There are two dashed lines because each of the unhybridized 2p orbitals has two areas of electron density, one above and one below the plane of the molecule, but only one π-bond.
sigma bond
a bond formed when two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting the two atomic nuclei
pi-bond (π-bond)
a covalent bond in which the bonding electrons are most likely to be found in sausage-shaped regions above and below the bond axis of the bonded atoms
Hybrid orbitals will have a shape determined by:
a linear combination of the orbitals housing the valence electrons - We will combine the orbitals in the valence shell to get the shapes of the corresponding hybrid orbitals.
In which of the following are hybrid orbitals formed?
covalently bonded atoms - Hybrid orbitals cannot exist in isolated atoms (because they are the result of bonded atoms) so they can only exist in covalently bonded atoms (i.e. sigma bonds).
In an energy diagram, sp3 hybridized orbitals are:
in between 2s and 2p orbitals
What must be true about an atom that is sp3d hybridized?
it can be found in the first period it can be found in the second period it can be found in the third period any atom can be sp3d hybridized answer: can be found in the thirdperiod In order to become sp3d hybridized, an atom must have access to d orbitals, which begin at n=3. Therefore, of the available choices, only the third period is possible.
A pi bond involves:
lateral orbital overlap & a node - Pi bonds involve the lateral overlap of p orbitals, in which the electron density is on either side of the internuclear axis. Along the axis, there is a node in which there is no probability of finding an electron.
The energy of an sp orbital will be:
less than that of a p orbital but greater than that of an s orbital - An sp orbital will have an energy in between those of the unhybridized s and p orbitals.
If an atom has sp3d hybridization, what electron-pair geometry will it exhibit?
trigonal bipyramidal - The sp3d hybridization corresponds to a trigonal bipyramidal geometry as they will occupy a five electron domain.
The triple bond in acetylene, C2H2, is composed of what type of orbitals?
two π-bonds formed from p orbitals and one σ-bond formed from sp hybrid orbitals - The sp hybrid orbitals of the two carbon atoms overlap end to end to form a σ-bond between the carbon atoms. The remaining hybridized sp orbitals form σ bonds with the two hydrogen atoms at the far ends of the two carbons. The two unhybridized p orbitals on each carbon are positioned such that they overlap side by side and, hence, form two π-bonds. The two carbon atoms of acetylene are thus bound together by one σ-bond and two π-bonds, giving a triple bond.
A hybridized atomic orbital can contain or participate in which of the following?
σ-bonds lone pairs of electrons single unpaired electrons (radicals) - A hybrid orbital can make σ-bonds, and both lone pairs and single unpaired electrons can occupy hybrid orbitals. π-bonds are made by overlap of unhybridized p orbitals.
