Final EXAM STUDY TEST
Draw a Lewis structure for each molecule or ion. H3COH
H I .. H--C -- O -- H I .. H
A molecule with five bonded atoms and no lone pairs on the central atom will assume a
trigonal bipyramidal electron and molecular geometry.
Consider the phosphorus pentafluoride molecule shown here. Is PF5 a nonpolar, ionic, or polar compound?
nonpolar (PF5)
What type of hybridization is found on the central iodine atom in I3−? sp2 sp3d2 sp3 sp sp3d
sp3d
What is the hybridization of the central atom of each of the following molecules? PCl5 BCl3 H2O
sp: sp^2: - BCl3 sp^3: - H2O sp^3d: - PCl5 sp^3d^2:
There are five electrons in the homonuclear diatomic ion Li2+. Molecular orbital theory predicts the following occupation of the orbitals. What is the bond order of Li2+? 0 1 0.5 2
0.5 EXAPLANATION:
Diamagnetic
all electrons are paired
What is the molecular geometry of phosgene, COCl2? Is the COCl2 molecule polar or nonpolar? seesaw, polar trigonal planar, nonpolar square planar, nonpolar trigonal planar, polar
trigonal planar, polar EXPLANATION: COCl2 has an asymmetric structure with 3 bonding groups, and as a result has trigonal planar geometry. The molecule is polar.
Paramagnetic
unpaired electrons
exceptions to the octet rule
* incomplete octet: elements that are stable w/ fewer than 8 e- in valence shell --> H(2), He (2), Li (2), Be (4), and B (6) *Expanded Octet: elements in period 3 or greater can hold more than 8 e- in valence shell --> P(10), S (12), Cl (14) *Odd # e-: any element w/ odd # of e- won't be able to distribute e- to give 8 to each atom
What is the Lewis symbol for germanium?
. . Ge . . According to the periodic table, germanium has four valence electrons because it is in group 4A. In a Lewis symbol, the valence electrons of elements are represented as dots surrounding the element symbol
Select the Lewis symbols for the ions in each ionic compound. CaO
. Ca^2+ [ : O : ]^2- . Ca has two valence electrons and O has six valence electrons. Calcium loses two electrons, to be left with an octet from the previous shell, while oxygen gains two electrons to complete its octet.
Draw a Lewis structure for each molecule or ion. BrO^-
.. .. [ : Br -----O : ]^- .. .. =14 total valance electrons
Write the Lewis Structure for the hypochlorite ion, ClO^-
.. .. [ : Cl ------O : ]^- .. .. The hypochlorite ion, ClO−, has the chlorine and oxygen atoms connected by a single bond with each atom having a complete octet with three lone pairs of electrons on each. Since the oxygen has a single bond and a complete octet, it has a formal charge of −1 whereas chlorine is neutral.
Draw a Lewis structure for each molecule or ion. O2^2-
.. .. [ : O ---- O : ]^2- .. .. =14 valence electrons
Write the Lewis Structure for SCl2
.. .. .. : Cl------ S -----Cl : .. .. .. The SCl2 molecule has 20 valence electrons (one sulfur and two chlorine atoms) with a central S atom singly bonded to two chlorine atoms with completed octets. The central S will have two lone pairs of electrons on it.
What is the formal charge of each atom in this Lewis structure (listed from left to right)? .. .. S ====== C ======= S .. ..
0,0,0 S: 6- [4 + 1/2 (4)] = 0 C= 4- [ 0 + 1/2 (8)] = 0 S: 6- [4 + 1/2 (4)] = 0
A polar covalent bond would have an electronegativity difference between
1.8 and 0.4 * Electrons shared unequally*
State the total number of valence electrons in SO2. 12 valence electrons 18 valence electrons 32 valence electrons 24 valence electrons
18 valence electrons
Determine the bond order for the N2+ ion.
2.5 EXPLANATION: The bond order is calculated by taking half the difference between the number of electrons in bonding orbitals and the number of electrons in antibonding orbitals, where an antibonding orbital is denoted with the symbol * (the σ∗2s�2�∗ in this diagram). Therefore, the bond order is (7−2)/2=5/2 because only two of the nine valence electrons occupy the antibonding molecular orbital.
How many valence electrons must be accounted for in the Lewis structure of chloroethane (C2H5Cl)? 24 18 13 20
20
What is the maximum number of bonds that can form in a molecule with a central atom containing five electrons in sp^3 hybrid orbitals? 1 2 3 4
3 EXPLANATION: Ammonia, NH3 with a central nitrogen atom, is an example of a compound with a central atom containing five electrons in sp^3 hybrid orbitals.
Determine the idealized bond angle for each molecule. CI4 NCl3 OF2 H2S
90∘: 180∘: 109.5∘: CI4 NCl3 OF2 H2S 120∘: EXPLANATION: The idealized bond angles for a tetrahedral electron geometry are 109.5∘; however, the actual bond angles for molecules may differ depending on how strongly each electron group repels other groups
Which elements can have expanded octets? Elements in the second row of the periodic table and beyond often exhibit expanded octets. Elements in the third row of the periodic table and beyond often exhibit expanded octets. Elements in the fourth row of the periodic table and beyond often exhibit expanded octets. Elements in the fifth row of the periodic table and beyond often exhibit expanded octets.
: Elements in the third period and beyond of the periodic table can have expanded octets due to the presence of empty d orbitals which allows them to form hypervalent molecules like PC15 and SF6.
Write the Lewis structure for CO.
:C ==(3 lines)== O: The most stable structure for CO (carbon monoxide) allows for the octet of each atom to be complete without introducing a formal charge. Based on the valence numbers of the atoms, the Lewis structure will contain 10 electrons. Note that, for carbon monoxide to follow the octet rule, both atoms will have a formal charge.
Consider the Lewis structure for PCl3. What are the approximate bond angles? 180∘ 90∘ < 109.5∘ 120∘
< 109.5∘
Bonding Group
A group of electrons involved in a chemical bonds including a: -- single bond -- double bond -- triple bond.
Of these elements, which element will form the most polar bond with fluorine? Boron, B Oxygen, O Carbon, C Nitrogen, N
Boron, B EXAPLANATION: Boron will form the most polar bond with fluorine. Electronegativity values increase from left to right across the periods of the periodic table and decrease down the column. Fluorine has the highest electronegativity value, so the element with the lowest electronegativity will have the most polar bond because it will have the greatest difference in electronegativity.
In looking at the bolded atoms in the answer choices, which pair consists of molecules having the same geometry? CH2CCl2 and CH2CH2 CH2O and CH3OH PCl3 and BF3 CO2 and SO2
CH2CCl2 and CH2CH2 Both molecules have the bolded carbon atom double bonded to the other carbon as well as single bonds to two other atoms.
Use the ionic bonding model to determine which has the higher melting point, KCl or CaO. Explain your answer. KCl has a higher melting point because the ions have larger charges. KCl has a higher melting point because the ions have smaller charges. CaO has a higher melting point because the ions have larger charges. CaO has a higher melting point because the ions have smaller charges.
CaO has a higher melting point because the ions have larger charges. Explanation: You would expect CaOCaO to have the higher melting point because, in our bonding model, the calcium and oxygen ions are held together in a crystalline lattice by charges of 2+ for calcium and 2− for oxygen. In contrast, the KCl lattice is held together by charges of 1+ for potassium and 1− for chlorine. According to Coulomb's law, as long as the spacing between the cation and the anion in the two compounds does not differ that much, the higher charges in CaO result in lower potential energy (more stability), and therefore a higher melting point. The experimentally measured melting points of these compounds are 776∘C for KCl and 2570∘C for CaO, in accordance with the model.
Which compound is most likely to contain ionic bonds? N2O HI CaS CO2
CaS In CaS, Ca is a metal whereas S is a nonmetal. In this compound, electrons move from Ca to S; the Ca atom becomes a positively charged ion while the S atom becomes a negatively charged ion. These oppositely charged ions attract one another, forming an ionic bond.
Rank the following elements in order of decreasing electronegativity ( most to least) Se Cl S As
Cl > S > Se > As When moving from right to left across a row of the periodic table, the value of electronegativity decreases; it also decreases when moving down a column of the periodic table. .
In the molecule FBr, which atom is the negative pole? F Br
F Explanation: F = 3.98 electronegativity Br= 2.96 electronegativity F has the higher electronegativity because it is bigger
Arrange the following molecules and ions in order of increasing bond order: H2, H2 +, He2 H2 < H2 + < He2 H2 + < H2 < He2 He2 < H2 < H2 + He2 < H2 + < H2
He2 < H2 + < H2 This ordering also tells us about the strength of bonding interactions. With a bond order of 0, He2 is unstable and MO theory predicts that this molecule will not form. Conversely, the bond order of 1 for H2 tells us that the H2 molecule is stable and forms single bonds. Interestingly, MO theory also predicts that it is possible for the H2 + ion to form, though it is less stable than H2.
net dipole moment
In a Lewis structure, if the orientation of the bond diploes do not cancel out the molecules have a net dipole moment and are polar. In a Lewis structure if the individual bond dipole moments cancel each other out the result is a nonpolar molecule.
What are the general trends in electronegativity values? Increase from left to right, decrease from bottom to top Decrease from right to left, increase from top to bottom Increase from left to right, decrease from top to bottom Decrease from left to right, increase from top to bottom
Increase from left to right, decrease from top to bottom
Using the electronegativity values, the Li-N bonds in Li3N are ________ non polar covalent ionic polar covalent
Ionic EXPLANATION: The electronegativity difference between Li (1.0) and N (3.0) is 2.0, which is a value above 1.8, predicting an ionic bond.
Consider the following element combinations. Classify the bonds formed between each pair as ionic, polar covalent, or nonpolar covalent qualitatively based solely on each element's position on the periodic table. Do not conduct calculations. P and I F and F S and Br O and I N and N Mn and Cl Mg and N Ba and O
Ionic: -- Ba and O -- Mg and N -- Mn and Cl Polar Covalent: -- O and I -- P and I -- S and Br Nonpolar covalent: -- F and F -- N and N
Use Lewis symbols to determine the formula for the compound that forms between each of the following pairs of elements. K and Se
K2Se
Arrange the following substances in order of decreasing magnitude of lattice energy. SrO KBr RbI BaS
Largest Magnitude Smallest Magnitude SrO BaS KBr RbI Explanation: Lattice energy, the energy associated with forming a crystalline lattice within an ionic solid, is affected by both ionic size and ionic charge. The magnitude of the ionic charge is directly proportional to the energy, so the larger the magnitude of the charge, the greater the lattice energy. In SrO and BaS, the product of ionic charges is (2+)(2−)=4−, while, in KBr and RbI, the product of ionic charges is (1+)(1−)=1−. Therefore, SrO and BaS will have a greater (more negative) lattice energy than KBr and RbI. In the compounds with the same magnitude of ionic charge, the difference in lattice energy is determined by the difference in the distance between the constituent ions. As you go down a group in the periodic table, atomic radii increase, so BaS has a greater distance between ions than SrO. The same applies to KBr and RbI; RbI has a greater distance between the ions than KBr as it consists of larger ions. According to Coulomb's law, the magnitude of lattice energy decreases as the distance between the ions increases, so the lattice energy of SrO is more negative than the lattice energy of BaS and the lattice energy of KBr is more negative than that of RbI. In summary, SrO is the compound with the greatest magnitude of lattice energy, BaS has a greater magnitude of lattice energy than KBr, and RbI is the compound with the lowest magnitude of lattice energy.
Determine the electron geometry bond angles for each molecule. CI4 NCl3 OF2 H2S
Linear : Tetrahedral: - CI4 - OF2 - NCl3 - H2S Trigonal Plantar: Trigonal bipyramidal: Each of these molecules has four electron groups. CI4 has four bonding groups and zero lone pairs, NCl3 has three bonding groups and one lone pair, and both OF2 and H2S have two bonding groups and two lone pairs. Therefore, the electron geometry (tetrahedral) is the same for each
Bond polarity increases with electronegativity difference between the atoms in the bond. Which combination of elements will be most likely to form an ionic compound? Nonmetal and nonmetal Metal and nonmetal Metal and metal
Metal and nonmetal
Which of the ionic compounds below would be expected to have the highest lattice energy? RbBr LiF MgO KF
MgO (highest lattice energy )
Which of the compounds below would contain polar covalent bonds? F2, N2O, KCl F2 only KCl only N2O only both F2 and N2O
N2O only
Ionic compounds are formed from ionic bonds, whereby an electron is transferred from the metal cation to the nonmetal anion. Ions form solid lattices of ions. Covalent compounds form solids through the attraction of two covalent molecules. Since the attraction between two covalent molecules is weak compared to the ionic bonds holding an ionic compound together, ionic compounds tend to have higher melting points. Which of the following compounds has the highest boiling point? I2 NaI HI IBr
NaI
In which cases do you expect deviations from the idealized bond angle? OF2 H2S CI4 NCl3
OF2 H2S NCl3 EXPLANATION: NCl3 has three bonding groups and one lone pair whereas OF2 and H2S have two bonding groups and two lone pairs. Lone pairs and double bonds take up more room than single bonds and they repel the bonding groups to a greater extent, resulting in smaller bond angles. For example, NH3 has bond angles of 107∘. Thus, only CI4 will have the idealized bond angles of 109.5∘.
What is the electron geometry of SF6? Trigonal bipyramidal Square pyramidal Square planar Octahedral
Octahedral (SF6)
What is the electron geometry of XeF4? Square pyramidal Octahedral Tetrahedral Square planar
Octahedral (XeF4)
What electron geometry is associated with sp3d2 hybridization? Trigonal planar Octahedral Tetrahedral Trigonal bipyramidal Linear
Octahedral (sp^3d^2)
Identify the pair that lists the element with the lower electronegativity value written first. N, P H, Li P, S O, N
P, S
In which cases do you expect deviations from the idealized bond angle? CS2 PCl3 CH2F2 SCl2
PCl3 SCl2 EXPALNATION: Since PCl3 and SCl2 both have lone pairs of electrons on the central atom, their bond angles should deviate from the idealized bond angle as lone pairs are more repulsive than bonding pairs of electrons. Although CH2F2 contains different atoms surrounding the central carbon (with no lone pairs on it), the bonding groups belong to the same type, so CH2F2 should not deviate from the idealized bond angle. CS2 has identical atoms symmetrically surrounding a central atom with no lone pairs on it, so CS2 should not deviate from the idealized bond angle.
Is N2+ diamagnetic or paramagnetic?
Paramagnetic EXAPLANATION: Since the N2+ molecular ion has an unpaired electron in its σ2p orbital, it has a net magnetic moment and will be attracted to an external magnetic field. Diamagnetic materials, which have only paired electrons in their atomic and molecular orbitals, are not attracted to external magnetic fields because the magnetic moments of opposite spins cancel each other.
Determine whether each molecule given below is polar or nonpolar. SCl2 SiH3Br PF3 SiO2 NCl3 CI4 OF2 H2S
Polar: - SCl2 - SiH3Br - PF3 - NCl3 - OF2 - H2S Nonpolar: - SiO2 - CI4 EXPLANATION: PF3 has an unsymmetric distribution of bonding pairs and lone pairs around the central atom and both are polar. SCl2 has bent molecular geometry and contains polar bonds and therefore is polar. SiH3Br has an unsymmetrical distribution of atoms (electronegativities) around the central atom and is polar. SiO2 has a symmetric distribution of bonding pairs around the central atom and is nonpolar.
Of the molecules AlCl3 and AlBr3, which has bonds that are more polar? Since the electronegativity difference between the atoms is smaller in AlCl3, it has bonds that are more polar when compound to the other compound. Since the electronegativity difference between the atoms is smaller in AlBr3, it has bonds that are more polar when compound to the other compound. Since the electronegativity difference between the atoms is greater in AlCl3, it has bonds that are more polar when compound to the other compound. Since the electronegativity difference between the atoms is greater in AlBr3, it has bonds that are more polar when compound to the other compound.
Since the electronegativity difference between the atoms is greater in AlCl3, it has bonds that are more polar when compound to the other compound.
Which statement best describes the electron arrangement around phosphorus in PCl3? Single bonds to three chlorine atoms and two lone pairs of electrons Single bonds to three chlorine atoms Single bonds to two chlorine atoms and one double bond to a chlorine atom Single bonds to three chlorine atoms and one lone pair of electrons
Single bonds to three chlorine atoms and one lone pair of electrons
What is the molecular geometry of BrF5? Trigonal bipyramidal Square pyramidal Octahedral Square planar
Square pyramidal EXPLANATION: A molecule with five bonded atoms and one lone pair on the central atom will assume an octahedral electron geometry and a square pyramidal molecular geometry.
Use Lewis symbols to determine the formula for the compound that forms between each of the following pairs of elements. Sr and Se
SrSe
What is the molecular geometry of ClF3? Trigonal bipyramidal T-shaped Trigonal planar Square pyramidal
T-shaped
The molecular geometry (shape) of CCl4 is __________. Tetrahedral Trigonal pyramidal Trigonal planar Linear
Tetrahedral (CCL4)
Determine the molecular geometry bond angles for each molecule. CI4 NCl3 OF2 H2S
Tetrahedral: - CI4 Trigonal Planar: Trigonal Pyramidal: Bent: - OF2 - H2S Linear: EXPLANATION: Although each of these molecules has four electron groups and a tetrahedral electron geometry, the molecular geometries are not identical because of the combinations of bonding groups and lone-pair electrons. CI4 has only four bonding groups and no lone pairs, making its electron geometry and molecular geometry the same, whereas NCl3 has three bonding groups and one lone pair, resulting in a trigonal pyramidal molecular geometry. The three bonding groups form a triangular base with the central atom above this plane and the lone pair vertically up, which results in the observed three-dimensional shape. Both OF2 and H2S have two bonding groups and two lone pairs. Two of the bonding groups occupy two of the tetrahedron's corners, and the two lone pairs occupy the other two of the tetrahedron's corners. Thus, the two bonding groups around the central atom form an obtuse bonding angle that determines the molecular shape, and the observed three-dimensional shape is bent
Which statement is true about the energy levels of bonding and antibonding orbitals? The energy of a bonding orbital may be greater than or less than the energy of the corresponding antibonding orbital. The energy of a bonding orbital is always lower than the energy of the corresponding antibonding orbital. The energy of a bonding orbital is equal to the energy of the corresponding antibonding orbital. The energy of a bonding orbital is always higher than the energy of the corresponding antibonding orbital.
The energy of a bonding orbital is always lower than the energy of the corresponding antibonding orbital. EXPLANATION: Two molecular orbitals form from two atomic orbitals, one bonding orbital, and one antibonding orbital. The bonding orbital is always lower in energy than the atomic orbitals from which it was formed, and the antibonding orbital is always higher in energy than the atomic orbitals from which it was formed. Therefore, the energy of the bonding orbital is always lower than the energy of the corresponding antibonding orbital.
The bond order provides a measure of the stability of a bond. Select the true statement. The higher the bond order, the more stable the bond. A negative bond order indicates a stable bond. The lower the bond order, the more stable the bond. A bond order of zero indicates a stable bond.
The higher the bond order, the more stable the bond. EXPLANANTION: Bond orders are calculated from the numbers of electrons in bonding and antibonding orbitals. The values are always positive; and the higher the value, the more stable the bond. Bond orders of zero are unstable and indicate that a bond will not form. Bond orders cannot be negative because the number of electrons in bonding orbitals will always be equal to or more than the number of electrons in antibonding orbitals.
Which statement is true? There is no connection between the number of standard atomic orbitals and the number of hybrid atomic orbitals. The number of standard atomic orbitals is less than the number of hybrid atomic orbitals. The number of standard atomic orbitals is greater than the number of the hybrid atomic orbitals. The number of hybrid atomic orbitals made equals the number of standard atomic orbitals used.
The number of hybrid atomic orbitals made equals the number of standard atomic orbitals used.
What is the electron geometry of XeF2? Linear Bent Trigonal bipyramidal Trigonal planar
Trigonal bipyramidal EXPLANATION: A molecule with two bonded atoms and three lone pairs on the central atom will assume a trigonal bipyramidal electron geometry.
How many covalent bonds are usually formed by the element O? One bond Four bonds Two bonds Three bonds
Two bonds
Do you expect the bond in the N2+ ion to be stronger or weaker than the bond in the N2 molecule?
WEAKER EXPLANATION: The N2 molecule has 10 valence electrons (one more than N2+), where 8 electrons occupy bonding molecular orbitals and 2 electrons occupy the antibonding molecular orbital (σ∗2s). Therefore, N2 has a bond order of 3. Since the bond order of N2+ is less than that of N2, it has a weaker bond.
When is it appropriate to form double or triple bonds in a Lewis structure? Anytime there is a bond from the central atom to oxygen Anytime a terminal atom has a lone pair of electrons When the central atom has an expanded octet When the central atom does not have an octet of electrons
When the central atom does not have an octet of electrons
Electron Group
a general term for a lone pair, single bond, or multiple bond in a molecule some number of electrons that share the same region of space in a molecule
Molecular Orbital Theory
a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.
Dipole
a molecule that has two poles, or regions, with opposite charges
If the difference in electronegativity (ΔEN) between two atoms is 1.5, how would the bond formed between those atoms be classified? pure covalent bond (nonpolar) hydrogen bond a polar covalent bond ionic bond
a polar covalent bond Explanation: According to the figure, polar covalent bonds have ΔEN values that fall in the range of 0.4 to 2.0. Thus, the bond with difference in electronegativity 1.5 is a polar covalent bond.
Rubidium iodide has a lattice energy of −− 617 kJ/molkJ/mol, while potassium bromide has a lattice energy of −− 671 kJ/molkJ/mol. Why is the lattice energy of potassium bromide more exothermic than the lattice energy of rubidium iodide? On the periodic table, rubidium is ______(a) potassium, and iodine is ____(b) bromine. Therefore, both the rubidium ion and the iodide ion have a ____(c) than the potassium ion and the bromide ion, respectively. Because of this, the rubidium ion and the iodide ion _____(d) the potassium ion and the bromide ion can, and the rubidium and iodide ions release less energy upon forming the crystal, as observed. The lattice energy of potassium bromide is ____(e) exothermic than that of rubidiumiodide. Word Bank: Smaller molar mass larger molar mass can get much closer to each other cannot get as close to each other larger atomic mass more above below less smaller atomic
a. below b. below c. larger atomic radius d. cannot get as close to each other e. more
How does lattice energy relate to ionic radii? As the ionic radii increase as you move ____(a) a group, the ions cannot get as close to each other and therefore _____(b) as much energy when the lattice forms. Thus, the lattice energy _____(c) (becomes less _____(d)) as the radius increases. Word Bank: Down do not release release negative up postive increases decreases
a. down b. do not release c. decreases d. negative
How does the electron sea model explain the conductivity of metals? The malleability and ductility of metals? Metals conduct electricity because the ______(a) in a metal are free to move. Within this model, the movement or flow of _____(b) in response to an electric potential is an electric current. Metals ____(c) conductors of heat because of the highly-mobile _____(d), which ______(e) able to disperse thermal energy throughout the metal. Malleability is the capacity to _____(f), while the ductility is the capacity to _____(g). Since _____(h), it can be deformed relatively easily by forcing the metal ions to slide past one another. Word Bank: ions electrons and ions are not electrons are there are not anions in a metal form strong and unbreakable structure metals have low electronegativity values there are not localized bonds in a metal be pounded into sheets be drawn into wires
a. electrons b. electrons c. are d. electrons e. are f. be pounded into sheets g. be drawn into wires h. there are no localized bonds in a metal
How does lattice energy relate to ion charge? Since the magnitude of the potential energy of two interacting charges depends not only on the distance between the charges but also on the product of the charges, the lattice energies become more _____(a) (more ____(b)) with increasing magnitude of ionic charge. Word Bank: endothermic exothermic negative positive
a. exothermic b. negative
What is the electron sea model for bonding in metals? In the sea model, the metal structure is formed during the donation of ____(a) electrons by each metal atom. Therefore, the structure is represented by metal cations that _____(b) fixed in space and electrons that are ____(c) within the structure. Word Bank: localized as each cation are not valence core all are delocalized
a. valence b. are c. delocalized
The three types of bonds are ______(a) bonds, which occur between metals and nonmetals and are characterized by _____(b); ______(c) bonds, which occur between nonmetals and are characterized by ______(d); and _____(e) bonds, which occur between metals and are characterized by _____(f). Word Bank: ionic van der Waals electrostatic diple-diple the transfer of electrons covalent the sharing of electrons metallic electrons being pooled
a.ionic b.the transfer of electrons c. covalent d. the sharing of electrons e. metallic f. electrons being pooled
A correct Lewis structure will show which atoms
are bonded to which other atoms and account for all of the valence electrons.
Expanded Octet
atoms that can have more than an octet; must be in 3rd period and below on periodic table
Both of the sulfur-oxygen double bonds in SO2SO2 are polar. In which direction should the polarity arrows point? to the right to the left toward the central sulfur atom away from the central sulfur atom
away from the central sulfur atom
Which pair of elements is most likely to form an ionic bond? barium and oxygen phosphorus and oxygen carbon and hydrogen sulfur and oxygen
barium and oxygen An ionic bond is a type of chemical bond involving the complete transfer of valence electron (or electrons) between atoms. An ionic bond requires an electron donor, often a metal, and an electron acceptor, a nonmetal. Oxygen and barium are most likely to form an ionic bond.
A nonpolar covalent bond would have an electronegativity difference
below 0.4 *Electrons shared equally*
What is the molecular geometry of water, H2O? Is the H2O molecule polar or nonpolar? trigonal planar, nonpolar trigonal planar, polar bent, polar bent, nonpolar
bent, polar EXPLANATION: H2O has an asymmetric structure with 2 bonding groups and 2 lone pairs and as a result has bent geometry. The molecule is polar.
Apply molecular orbital theory to determine the bond order of Ne2.
bond order of Ne2= 0.0 EXPLANATION: The bond order is calculated by taking half the difference between the number of electrons in bonding orbitals and the number of electrons in antibonding orbitals, where the antibonding orbitals are denoted with the symbol * (the σ∗2s, π∗2p, and σ∗2p orbitals in this diagram). Therefore, the bond order is (8−8)/2=0because there are an equal number of electrons in bonding and antibonding molecular orbitals (and Ne2 would have a total of 16 valence electrons). This signifies that Ne2 should not exist, and there is no evidence of it being observed in nature.
Terminal Atom
bonded to only one other atom an atom that goes on the end of a lewis structure
Ionic Compound
composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal
Carbon tetrafluoride (CF4CF4) is used as a low-temperature refrigerant in refrigerators. What type of bonding occurs between the atoms of a CF4 molecule? covalent metallic ionic
covalent (CF4)
Valence bond theory is based on the idea that _________. all orbitals of an atom form a single hybridized orbital electrons move from atomic orbitals to hybrid orbitals electrons in atomic or hybrid orbitals overlap to form bonds
electrons in atomic or hybrid orbitals overlap to form bonds
An ionic bond would have an electronegativity difference
greater than 1.8 *Electron transferred*
If there is a large electronegativity difference between the two elements in a bond, such as normally occurs between a metal and a nonmetal, the electron from the metal is almost completely transferred to the nonmetal, and the bond is ______.
ionic
What type of bonding occurs in sodium chloride, NaCl? covalent metallic ionic
ionic (NaCl)
For elements in the periodic table, electronegativity increases from
left to right and decreases from top to bottom.
What is the molecular geometry of carbon dioxide, CO2?CO2? Is CO2 molecule polar or nonpolar? linear, polar linear, nonpolar trigonal pyramidal, polar T-shaped, nonpolar
linear, nonpolar EXAPLANATION: CO2 has a highly symmetric structure with 2 bonding groups, and as a result has linear nonpolar geometry. The molecule is nonpolar.
hat type of bonding occurs in a sample of pure copper, Cu? In other words, how is one copper atom held to another copper atom? covalent metallic ionic
metallic (Cu)
Consider the Lewis structure of carbon dioxide. What type of hybridization is found on carbon in CO2?
sp EXPLANATION: Look at the Lewis structure of CO2 to determine that the electron group geometry around the carbon is linear. Molecules with linear electron group geometry have sp hybridization.
Consider the xenon tetrafluoride molecule shown here: Is XeF4 a nonpolar, polar, or ionic compound?
non polar EXAPLANANTION: The Xe-F bonds are polar because of their difference in electronegativity values. Due to the molecular geometry (shape) of the molecule, which is square planar, the polarity of the bonds results in a net dipole moment of zero so the molecule is nonpolar.
The bonding predicted by electronegativities in Cl2 is nonpolar covalent ionic polar covalent
nonpolar covalent EXPLANATION: The electronegativity difference between Cl (3.0) and Cl (3.0) is 0.0, which is a value below 0.4, predicting a nonpolar covalent bond
A Lewis structure may be adapted to show the shape of the molecule, but the molecular shape is
not necessarily shown in a Lewis structure.
A molecule with six bonded atoms and no lone pairs on the central atom will assume a
octahedral electron and molecular geometry.
A molecule with four bonded atoms and two lone pairs on the central atom will assume a
octahedral electron geometry and a square planar molecular geometry.
A double bond is composed of
one ơ and one π(pi) bond
A triple bond is composed of
one ơ and two π bonds
If there is an intermediate electronegativity difference between the two elements, such as between two different nonmetals, the bond is _______.
polar covalent
Using electronegativity values, the C-Cl bonds in CCl4 are __________. non polar covalent ionic polar covalent
polar covalent EXAPLANATION: The electronegativity difference between C (2.5) and Cl (3.0) is 0.5, which is a value below 1.8 but above 0.4, predicting a polar covalent bond.
We use Valence Shell Electron Pair Repulsion theory to
predict the shape of the molecule from its Lewis structure.
What type of bond would you expect to form between I and BrBr in iodine monobromide, IBr? Electronegativity for I is 2.5 and for BrBr is 2.8. ionic bond hydrogen bond polar covalent bond pure covalent bond (nonpolar)
pure covalent bond (nonpolar) Explanation: Iodine's electronegativity is 2.5 and bromine's is 2.8, so ΔEN=0.3, making the bond nonpolar covalent.
If two elements with identical electronegativities form a covalent bond, they share the electrons equally, and the bond is ______ or nonpolar.
purely covalent
In resonance structures, the valence electrons are
redistributed among the atoms while continuing to satisfy the octet rule.
Consider the Lewis structure of chloromethane. What type of orbitals overlap to form the C-Cl bond in CH3Cl? p of carbon and p of chlorine p of carbon and sp3 of chlorine sp3 of carbon and p of chlorine s of carbon and p of chlorine
sp3 of carbon and p of chlorine EXPLANATION: The carbon in CH3Cl has a tetrahedral electron group geometry and sp3 hybridization. The sigma bond between carbon and chlorine is formed from the overlap of a hybrid sp3 orbital of carbon and a half-filled p orbital of chlorine.
Each of the structures for ClOCl, NCOH, and ClNO has atoms connected in the order given in their formulas. Identify the type of hybridization for the central atom in each compound. carbon in NCOH nitrogen in CINO oxygen in CIOCl
sp: carbon in NCOH sp^2 nitrogen in CINO sp^3: oxygen in CIOCl EXPLANATION: NCOH is cyanic acid, although the species exists more commonly as HNCO, with the hydrogen atom attached to the nitrogen atom, which is called isocyanic acid. In isocyanic acid, carbon has two double bonds, one to oxygen and one to nitrogen, and is still sp hybridized.
What is the hybridization for Xe in the XeF2 molecule? sp^2 sp^3 sp sp^3d
sp^3d
Incomplete Octet
stable with fewer than eight electrons and include H, He, Li, Be, and B
Determine the molecular geometry of CH4. tetrahedral octahedral trigonal bipyramidal trigonal planar
tetrahedral CH4 has 4+4×1=8 valence electrons. The carbon atom has four electron groups: four single bonds. The electron geometry that minimizes the repulsions between four electron groups is tetrahedral. The four bonds are equivalent, so they each exert the same repulsion on the other three and cause the molecule to assume a three-dimensional tetrahedral geometry with 109.5∘ between each bond.
Hybridization
the mixing of several atomic orbitals to form the same total number of equivalent hybrid orbitals
Hybrid atomic orbitals form from standard atomic orbitals, and when they do:
the number of hybrid atomic orbitals made equals the number of standard atomic orbitals used.
A single bond is a
ơ (sigma) bond
