Chemistry II- Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals
A central atom can be surrounded by 5 or 6 electron pairs if __________ orbitals are available for bonding. The appropriate number of equivalent bonding orbitals is formed by combining_____________s orbital(s), ________________p orbital(s), and 1 or 2 orbitals.
- d -one -three -d
The structure shown contains_________σ bond(s) and _______π bond(s)
-6 -2
Match each definition with the correct term in relation to molecular polarity. Nonpolar molecule Polar molecule
-A molecule having no dipole moment -A molecule having a dipole moment
Which of the following options correctly describe the structure shown? Select all that apply.
-C1 will have a tetrahedral geometry -C2 will have a linear geometry -The bond angles around C2 are approximately equal to 180°
Which of the following are limitations of Lewis bond theory? Select all that apply.
-Lewis theory doesn't consider the nature of the atoms that share the bonding electrons. -Lewis theory provides no explanation for the differences among covalent bonds.
Match each type of orbital hybridization with the corresponding geometry. sp sp² sp³ sp³d sp³d²
-Linear -Trigonal planar -Tetrahedral -Trigonal bipyramidal -Octahedral
Which two quantum mechanical theories are used to describe covalent bond formation?
-Molecular orbital theory -Valence bond theory
The boron atom in the structure shown requires 3 equivalent bonding orbitals, which are formed by combing __________ s and ___________ p orbital(s) from the boron atom to form 3 equivalent _________ hybrid orbitals. There is (are) _______ unhybridized p orbital(s) on the boron atom, which contain(s) no electrons.
-One -Two -sp₂ -One
Why is the hybridization model necessary to explain the bonding in a molecule such as CH4? Select all that apply.
-The atomic electron configuration of carbon cannot account for four equivalent bonds. -The observed bond angles cannot be explained with reference to unhybridized orbitals.
For each type of hybrid orbital, select the correct number and type of unhybridized orbitals that remain in the valence shell. sp sp3d sp2 sp3 sp3d2
-Two p orbitals -Four d orbitals -One p orbitals -None -Three d orbitals
The arrangement of 5 electron pairs around a central atom is trigonal _______. This system has two different bond angles. Three groups lie in a trigonal plane around the central atom with bond angles of_________°, whereas the other two groups lie above and below this plane, at an angle of _______° to the trigonal plane.
-bipyramidal -120 -90
The polarity of a bond can be expressed in terms of its ______moment (symbol μ), which is the product of the partial charge in the bond and the ______ between the bonded atoms.
-dipole -distance
Match each description of polarity with the correct statement. -Individual bond dipoles will cancel -Individual bond dipoles will not cancel -A species will be nonpolar overall -A species will be polar overall
-for a species that has identical bonds and a symmetrical geometry -for a species with an unsymmetrical geometry -if individual bond dipoles cancel -if individual bond dipoles do not cancel
A bond formed by the overlap of two s orbitals or the end-to-end overlap of two orbitals that p character is called a(n) _______ bond. This bond has its highest electron density between the _______ of the two bonded atoms.
-sigma -nuclei
The combination of one s and two p orbitals will form a group of three________ hybrid orbitals. These hybrid orbitals adopt a(n) ____________planar geometry, and the angle between any two of them is ____________°.
-sp2 -trigonal -120°
According to the VSEPR model, each pair of _________electrons around a central atom will be located as far away from the others as possible, in order to minimize electron-electron
-valence -repulsion
Place the steps for determining the geometry of covalently bonded species in the correct order. Start with the first step at the top of the list.
1: Draw the Lewis structure of the molecule, considering only the electron pairs around the central atom. 2: Count the total atom number of electron pairs around the central atom. 3: Predict the geometry of the molecule. 4: Predict the bond angles in the molecule.
The structure shown contains___________σ bonds and _________π bonds.
6;2
The Lewis structure for the AsF6 is shown.n The approximate value of the bond angle marked "a" is equal to_________, whereas the approximate value of the bond angle marked "b" is equal to _______. ( Remember that this species is NOT flat, as indicated by the wedged and dashed bonds).
90°; 120°
Which of the following options correctly defines a polar bond?
A bond in which the shared electron pair is distributed unevenly between the atoms
Match each of the structure shown correctly to its geometry. Note that in the line illustration, lone pairs have been excluded from the terminal atoms for simplicity.
A-Trigonal bipyramidal B-Tetrahedral C-Trigonal planar D-Linear E-Octahedral
Match each of the three- electron pair systems with the correct geometry.
AB3 - Trigonal planar AB2E - Bent
Match each 5-electron pair system with the correct geometry.
AB₅ - Trigonal bipyramidal AB₄E- Seesaw AB₃E₂- T-shaped AB₂E₃- Linear
Match the designations for a system with 6 electron pairs to the appropriate geometry.
AB₆ - Octahedral AB₅E- Square pyramidal AB₄E₂- Square planar
Why are the terms "axial" and "equatorial" not used to describe the bonds in an octahedral system?
All six bonds are equivalent in an octahedral system.
Explain why BeF₂ is a nonpolar molecule.
BeF₂ is linear and therefore the individual bond dipoles cancel to give no net dipole.
According to the VSEPR model, which of the following determines the geometry around a central atom in a Lewis structure?
The number of valence-shell electron pairs
Molecular geometry is the spatial arrangement of _______ in a molecule.
atoms
A 5-electron pair system (shown) has two different types of positions for substituents. The three positions marked "1" form a trigonal plane about the central atom and are called ________ positions, whereas the two positions marked "2" are ______ positions.
equatorial, axial
Lone pairs are associated with __________ atom(s), giving them________ spatial distribution than bonding electrons. For this reason, lone pairs experience greater repulsion from neighboring lone pairs and bonding pairs.
one, more
The _________ shell is the outermost electron-occupied shell in an atom. (Use the specific term used to describe the outer shell)
valence
What approximate value will be observed for the bond angle marked in the structure shown? (Note that Lewis structures commonly do not reflect the actual shape of the species.)
Less than 109.5°
Match each molecular geometry with the correct general formula.
Linear- AB₂ Trigonal planar-AB₃ Tetrahedral-AB₄ Trigonal bipyramidal-AB₅ Octahedral-AB₆
Which of the following statements correctly describe sp³ hybrid orbitals? Select all that apply.
-An sp³ hybrid orbitals is unsymmetrical in shape, having one small and one large lobe. -The four sp³ hybrid orbitals of a group are equivalent in shape and energy.
Molecular geometries are classified by assigning a specific ABx designation to a structure. Match each symbol in this designation with its correct meaning. A x B
-Central atom in structure -Number of bonding electron groups -Surrounding atom
Which of the following options correctly describe sp hybrid orbitals? Select all that apply.
-Each sp hybrid orbital has one large and one small lobe. -The energy of an sp hybrid orbital lies between the energies of the original s and p orbitals that were mixed.
Which of the lettered options correspond to equatorial positions in the image shown? Select all that apply.
b,c,d
Which of the species in the following list have a net dipole moment (i.e., are polar overall)? Select all that apply.
-CHCl₃ -NBr₃
Which of the following options correctly describe a covalent species that has 4 electron pairs around the central atom? Select all that apply.
-If all 4 electron pairs are bonding pairs, the shape of the system is tetrahedral. -The predicted bond angle for a system with 4 electron pairs is 109.5° -A bent shape is observed if there are 2 bonding pairs and 2 lone pairs.
Which of the following statements correctly describe KrBr₂? Select all that apply.
-Kr is surrounded by 5 electron pairs -Kr is surrounded by 3 lone pairs
Which of the following statements correctly defines hybrid orbitals?
-Orbitals used for bonding that are formed by mixing atomic orbitals from the same atom.
In general, the smaller the bond angle, the _____________ the electron repulsions for the electron pairs concerned. In a five-electron pair system, lone pairs prefer to occupy__________ positions because equatorial-equatorial repulsions are_________than axial-equatorial repulsions.
stronger, equatorial, weaker
Which of the following statements correctly describe the rules used to govern the application of the VSEPR model? Select all that apply.
-Multiple bonds are treated as single bonds -Multiple bonds take up more space than single bonds.
Arrange the steps for determining they hybridization of an atom in the correct order.
1: Draw a Lewis structure using the molecular formula 2: Count the number of electron pairs surrounding the central atom. 3: From the VSEPR model, deduce the geometry of the molecule. 4: Match the appropriate hybrid orbital designation with the correct electron pair arrangement,
Order the following repulsive forces from greatest to least. Put the pair with the greatest repulsive forces at the top of the list.
1: Lone-pair versus lone-pair repulsion 2: Lone- pair versus bonding-pair repulsion 3: Bonding-pair versus bonding-pair repulsion
A double bond is always made up of ________ σ________π bond(s). A double bond is ________ than a single bond.
1;1; stronger
Select the partial orbital that correctly shows the hybrid orbitals and electron distribution of the N atom in the molecule NBr3.
C
True or false: Any molecule in which all of the bonds are identical will be nonpolar.
False
Match the symbols correctly to describe the uneven charge distribution in on O-H bond of the H2O molecule.
H- Partially positive charged (δ+) O- Partially positive charged (δ-)
Which of the following statement correctly defines hybrid orbitals?
Orbitals used for bonding that are formed by mixing atomic orbitals from the same atom
The __________ around a central atom in a molecule is used to determine its.
geometry, hybridization
Valence bond theory proposes that before a covalent bond forms, atomic orbitals form a given atom can combine to form new atomic orbitals, This process is called______________ of orbitals, and the new atomic orbitals are referred to as ________________ orbitals.
hybridization; hybrid
Match each molecular geometry with the correct bond angle(s) Linear Trigonal planar Tetrahedral Trigonal bipyramidal Octahedral
-180° -120° -109.5° -180°, 120°, 90° -180°, 90°
Which of the following statements correctly describe a π bond? Select all that apply.
-A π bond is formed by the side-to-side overlap of two p orbitals - A multiple bond always contains at least one π bond
The Lewis structure for the molecule SeF6 is shown. Which of the following statements correctly describe the bonding in this molecule? Select all that apply.
-Se has an expanded octet. -The unhybridized d orbitals on Se contains no electrons -The Se atom in this molecule is sp3d2- hybridized
Which of the following options correctly describe a dipole moment?
-The dipole moment provides a quantitative measure of bond polarity. -A dipole moment arises when a bond or a molecule has an uneven distribution of electron density.
A particular hybrid orbital is designated sp³d². What information is provided by the superscripts in this designation?
-The number of each type of atomic orbital combined to produce this type of hybrid orbital.
Which of the following statements correctly describe hybrid orbitals? Select all that apply.
-The type of hybrid orbital varies depending on the specific combination of atomic orbitals -The shape and orientation of a hybrid allow maximum overlap with an orbital from another atom to form a bond -The spatial orientations of the hybrid orbitals match observed molecular shapes.
The molecular shape of a covalent species is determined not only by the number of __________ electron pairs that join the atoms, but by the number of __________ electron pairs as well, since these electrons also occupy space.
-bonding -nonbonding
To classify the geometry, a structure is assigned a specific ABxEy designation, where A is the ___________ atom, B is a(n) ____________ atom, and E represents a (n)__________ pair.
-central -surrounding -lone
Six electron pairs around a central atom form a(n) _____________ arrangement with bond angles of ___________ degrees
-octahedral -90
Six electron pairs around a central atom form a(n) ________ arrangement with bond angles of _________ degrees.
-octahedral -90
Arrange the steps for determining the hybridization of an atom in the correct order.
1: Draw a Lewis structure using the molecular formula 2: Count the number of electron pairs surrounding the central atom 3: From the VSEPR model, deduce the geometry of the molecule 4: Match the appropriate hybrid orbital designation with the correct electron pair arrangement,
Valence bond theory describes a single covalent bond as the _______ of orbitals from two atoms to form a shared space, which is occupied by ______ electron(s).
overlap; two
The triple bond in the structure shown consists of an σ bond formed by the overlap of a(n) ______ orbital on the C with a(n) _______ orbital on the N to form the σ bond. The π bonds are formed by the overlap of two pairs of _______ orbitals.
sp, sp, p
