Chemistry Chapter 8

bond order

(total number bonding pairs)/(number of bond locations)

How many lone pairs on the central atom does HCl have?

3

From which subshell are electrons first lost when tungsten becomes ionized?

6s

Oxidation number

The "charge" that results when electrons in a covalent bond are assigned to the more electronegative atom

What is the oxidation number on the S atom in sulfuric acid, H₂SO₄? a. +6 b. 0 c. +8 d. -4 e. +4

a

Which of the following do you predict to be the least polar covalent bond? a. N-S b. N-As c. N-Se d. N-F e. N-Br

a

Which of the following statements is correct with respect to atomic radius size for the species being compared? Select ALL the correct answers, this is a multiple response question a. O2- is larger than O b. Se is larger than Se2- c. Na is larger than Na+ d. Mg2+ is larger than Mg

a and c

Electron affinity

a measure of how strongly an atom attracts an external electron

Ionization energy

a measure of how strongly an atom holds on to its electrons

Electronegativity

a measure of how strongly an atom in a molecule attracts shared electrons in a covalent bond

In the Lewis structure for SF4, S has ___(i)_____ lone pairs of electrons and _____(ii)______bonded pairs of electrons. a. 1, 4 b. 0, 4 c. 0, 5 d. 2, 4 e. 1, 5

a.

Which of the following is a correct definition of electronegativity? a. The energy change that occurs when a neutral atom gains an electron b. the ability of an atom in a molecule to attract electrons to itself c. The energy required to remove an electron from the neutral atom d. both (a) and (c) are correct definitions of electronegativity e. all of the above are correct definitions of electronegativity

b.

How many equivalent resonance structures can be drawn for sulfur trioxide where all atoms obey the octet rule? a. just one structure, there is no resonance b. 2 c. 3 d. 4 e. 5

c.

In the Lewis structure for ICl₂⁻ , where I is the central atom, I contains ___(i)_____ nonbonded electrons and _____(ii)______bonded electrons. a. 6, 6 b. 0, 8 c. 2, 6 d. 4, 4 e. 6, 4

e

In the Lewis structure for sulfur trioxide where all atoms obey the octet rule, what is the formal charge on S? a. -2 b. -1 c. 0 d. +1 e. +2

e

Listed below are different chemical species. Which set contains species that are all isoelectronic, AND are also arranged properly in the order of smallest (first) to largest (last) radius? a. Sb3-, As3-, P3-, N3- b. N3-, P3-, As3-, Sb3- c. Ar, Kr, Cl-, Br⁻ d.P3, S2-, Ar, Ca2+ e. Ca2+, Ar, S2-, P3-

e

metal + nonmetal: type of molecule....type of bond

ionic; ionic

Isoelectronic species

same number of total electrons

covalent bonding

sharing of valence electrons between atoms, usually nonmetal + nonmetal

metal + metal: type of molecule....type of bond

solid metal; metallic

Multiple bonds, when formed between two defined atoms such as C and N, tend to be ____(i)_______ and _____(ii)________ than single bonds.

stronger; shorter

Lattice energy

the energy required to separate one mol of an ionic compound into its constituent gaseous ions

Molecular bonding

the forces that hold adjacent atoms in a molecule together

Molecular structure

the way atoms are arranged in molecules and polyatomic ions

Lewis dot symbols

valence electrons only, place electrons on four sides, place single electrons on all sides before pairing,

How many lone pairs on the central atom does H₂S have?

2

How many lone pairs on the central atom does CH₄ have?

0

How many lone pairs on the central atom does CO₂ have?

0

How many lone pairs on the central atom does SO₃ have?

0

How many lone pairs on the central atom does SiCl₄ have?

0

How many lone pairs on the central atom does NF₃ have?

1

What is the oxidation number of C in the oxalate ion, C₂O₄²⁻? a. +4 b. +6 c. +3 d. +2 e. -2

c

Which of the following anions would have the greatest lattice energy when combined with Mg²⁺ in an ionic compound? a. chloride b. selenide c. nitride d. phosphide e. sulfide

c

What is the electron configuration for the Molybdenum (III) ion, Mo³⁺

[Kr]5s⁰4d³

A certain elemental ion that is isoelectronic with Ar has valence electrons that feel Zeff = +10. What is the ion charge on this ion? a. +2 b. +1 c. -1 d. -2 e. -3

a

Draw possible Lewis structures for the thiocyanate anion, SCN⁻, where C is the central atom. Note that N is more electronegative than S. In the best Lewis structure based on formal charge considerations: a. there is a C-N double bond and a C-S double bond b. there is a C-N single bond and a C-S triple bond c. there is a C-N triple bond and a C-S single bond d. there is a C-N single bond and a C-S double bond e. there are no multiple bonds

a

Order the following atoms from lowest to highest electronegativity: O, F, P, S, Ga, As a. Ga < As < P < S < O < F b. Ga < As < P < O < S < F c. Ga < As < S < P < O < F d. Ga < P < As < S < O < F

a

Octet rule

atoms gain, lose, or share electrons in ways that allow them to be surrounded by 8 valence electrons

4. Formaldehyde has the chemical formula H2CO, where C is the central atom. In the Lewis structure for formaldehyde, O has ___(i)_____ lone pairs of electrons and _____(ii)______bonded pairs of electrons. a. 3, 1 b. 2, 2 c. 0, 4 d. 1, 3 e. 4, 0

b

A certain elemental ion that is isoelectronic with Ar has valence electrons that feel Zeff = +6. This ion could be formed from which atom? a. P b. S c. Ca d. K e. more than one of the above

b

For the carbon atom of carbon monoxide, the formal charge is ___(i)_____ and the oxidation number is _____(ii)_____. a. (i) +1; (ii) +1 b. (i) -1; (ii) +2 c. (i) 0; (ii) +1 d. (i) +1 ; (ii) +2 e. (i) +2; (ii) +2

b

How many equivalent resonance structures can be drawn for the sulfate ion, SO4 2-, drawn in the form where the central S atom bears a formal charge of +1? a. 2 b. 4 c. 6 d. 8 e. only one structure, there is no resonance

b

Which of the following cations would have the greatest lattice energy when combined with S2- in an ionic compound? a. K+ b. Ca2+ c. Rb+ d.Cs+ e. Ba2

b

Which of the following is the most polar covalent bond? a. Si-F b. Ge-F c. N-O d. N-P e. N-S

b

Which of the following statements is/are false? Select all the false statements, this is a multiple response question. a. it always takes energy to break a chemical bond b. it always releases energy when a chemical bond is broken c. it may take energy to break a chemical bond, or release energy when a chemical bond is broken, depending on the type of chemical bond d. for two defined atoms bonded together, double bonds require more energy to break than single bonds e. for two defined atoms bonded together, double bonds release more energy when broken than single bonds f. for two defined atoms bonded together, double bonds require less energy to break than single bonds g. for two defined atoms bonded together, double bonds release less energy when broken than single bond

b., c., e., f., and g.

Which of the following are isoelectronic with As3-? Select ALL the correct answers, this is a multiple response question. a. Ar b. Mo6+ c. S2- d. O2- e. Se2- f. Brg. P3- h. N3- i. Ca2+ j. Sr2+ k. K+

b., e., f., and j.

Formal charge

bookkeeping for valence electrons, #of valence electrons in isolated atom minus # of assigned electrons

How many equivalent resonance structures can be drawn for the sulfate ion drawn in the form where the central S atom bears a formal charge of 0? a. 2 b. 4 c. 6 d. 8 e. only one

c

In drawing Lewis structures for the following species, which one has an atom that does not satisfy the octet rule? a. CO b. CO2 c. NO d. NO2⁻ e. NO3⁻

c

In drawing all possible resonance structures for SO3 where all atoms obey the octet rule, what is the "average bond order" for each chemical bond? a. 1 b. 1and 1/2 c. 1 and 1/3 d. 1 and 1/4 e. 2

c

In the Lewis structure for SO3²⁻ , where all atoms satisfy the octet rule, S has ___(i)_____ lone pairs of electrons and _____(ii)______bonded pairs of electrons. a. 0, 3 b. 0, 4 c. 1, 3 d. 1, 4 e. 1, 5

c

A N-O single bond has a bond length of 136 pm. A N-O double bond has a bond length of 115 pm. What do you predict the N-O bond lengths will be in the nitrite ion, NO₂⁻? a. they will both be 136 pm b. they will both be 115 pm c. One will be 136 pm and one will be 115 pm d. They will both be about 125 pm e. No prediction can be made based on the information given

d

For the carbonate ion, CO₃²⁻, (i) how many equivalent resonance structures can be drawn, and (ii) what is the formal charge on C in this structure? a. (i) 1 (ii) +1 b. (i) 2 (ii) 0 c. (i) 2 (ii) +1 d. (i) 3 (ii) 0 e. (i) 3 (ii) +1

d

In order to satisfy the octet rule, which of the following atoms will want to form 3 bonds? a. Li b. B c. Al d. N e. S

d

In the Lewis structure for IBr₄⁻ , I has ___(i)_____ nonbonded electrons and _____(ii)______bonded electrons. a. 0, 8 b. 2, 8 c. 2, 4 d. 4, 8 e. 4, 2

d

The Lewis structure of the borate ion, BO₃³⁻ is drawn in a form that violates the octet rule for B. This is because: a. Boron, being in group 3A of n = 2, can only accommodate 3 chemical bonds b. There are an insufficient number of total electrons available for all the atoms in the borate ion to have an octet c. B is too electropositive to satisfy the octet rule in compounds d. The greater electronegativity of O precludes formation of a B-O double bond in the borate ion e. all of the above are correct

d

The carbonate ion, CO3 2-, contain how many total valence electrons? a. 28 b. 32 c. 22 d.24 e. 20

d

What is the formal charge on the central oxygen atom of ozone, O3? a. -2 b. -1 c. 0 d. +1 e. +2

d

Which of the following is NOT isoelectronic with Kr? a. As3- b. Rb+ c. Y3+ d. Ie. all of these are isoelectronic with Kr

d

Which of the following are isoelectronic with the sulfate ion? Select ALL the correct answers, this is a multiple response question. Use your knowledge of "hypo, "per", "ite, and "ate" , and your exam info sheet that has a list of common polyatomic ions, if necessary, to guide you. Note the chemical formula for the borate ion is given since you haven't encountered it yet. a. aluminum hydroxide b. sulfite ion c. carbonate ion d. phosphate ion e. chlorite ion f. chlorate ion g. perchlorate ion

d and g

Which of the following is a correct definition for "lattice energy" according to Wikipedia (http://en.wikipedia.org/wiki/Lattice_energy)? a. (a) The energy required to form one mole of an ionic compound from the constituent elements in their standard state forms b. (b) The energy released when forming one mole of an ionic compound from the constituent elements in their standard state forms c. (c) The energy released when forming one mole of an ionic compound from the constituent gaseous ions d. (d) The energy required to separate one mol of an ionic compound into the constituent gaseous ions e. Both (c) and (d) can be used to define "lattice energy", as long as you are careful to report the sign properly (negative or positive)

e

In the Lewis structure for ICl3, I has ___(i)_____ lone pairs of electrons and _____(ii)______bonded pairs of electrons. a. 1, 4 b. 2, 4 c. 0, 3 d. 1, 3 e. 2, 3

e.

What is the oxidation number on chlorine in the perchlorate ion, ClO₄⁻? a. +6 b. +5 c. +4 d. +3 e. +7

e.

nonmetal + nonmetal: type of molecule....type of bond

molecular; covalent