Gen Chem Ch. 5 Pearson Questions

Of the following elements, which has the highest electronegativity?

P

Si

Ca

Ge

Answer: P

Explanation: electronegativity increases up and to the right

Of the following elements, which has the lowest electronegativity?

I

Sr

Ca

Br

Answer: Sr

Explanation: electronegativity increases up and to the right

Choose the bond below that is most polar.

H-Cl

H-I

H-Br

C-H

H-F

Answer: H-F

Explanation: Florine is the most electronegative element. The most polar means the greatest difference in electronegativity between the two elements.

Find the two elements that are furthest apart using the increasing electronegativity rule.

Using periodic trends, place the following bonds in order of increasing ionic character.

Si-P Si-Cl Si-S

Si-P < Si-Cl < Si-S

Si-P < Si-S < Si-Cl

Si-Cl < Si-P < Si-S

Si-S < Si-Cl < Si-P

Si-Cl < Si-S < Si-P

Answer:   Si-P < Si-S < Si-Cl

Explanation: Find the two elements that are furthest apart using the increasing electronegativity rule.

Choose the bond below that is least polar.

P-F

C-F

C-I

C-Cl

C-Br

Answer: C-I

Explanation: C-I is least polar because the difference in electronegativity is the least

Place the following elements in order of increasing electronegativity.

Li Fr P

Fr < Li < P

Fr < P < Li

P < Li < Fr

P < Fr < Li

Li < P < Fr

Answer: Fr < Li < P

Explanation: increasting electronegativity = up and to the right

Place the following elements in order of decreasing electronegativity.

S F Te

S > F > Te

Te > F > S

F > S > Te

Te > S > F

F > Te > S

Answer: F > S > Te

Explanation: increasting electronegativity = up and to the right

List the following compounds in decreasing electronegativity difference.

Br₂ HBr KBr

HBr > KBr > Br₂

KBr > Br₂ > HBr

KBr > HBr > Br₂

Br₂ > HBr > KBr

Answer: 

Explanation:
find the electronegativities of each compound

use the relative distances between the compound’s elements coupled with the “up and to the right” electronegativity trend

Br₂ = Br to Br = 0 (meaning nonpolar)

HBr = H to Br = very long distance (polar)

KBr = K to Br = on opposite ends of the same row

This would mean the order is:   KBr > HBr >Br₂

Give the number of valence electrons for SCl₄

30

34

32

28

Answer: 34

Explanation: 6 + 7×4 = 34

Give the number of pairs of valence electrons for BBr3.

8

12

14

10

16

Answer: 12

Explanation: 3 + 3×7 = 24 valence / 2 = 12 pairs of valence

Choose the best Lewis structure for BeF2.

see attached image for answer choices

Answer: see attached image for correct answer

Choose the best Lewis structure for OCl₂.
see attached image for answer options

Answer: see attached image for correct answer

Choose the best Lewis structure for CH₂Cl₂
see attached image for answer options

Answer: see attached image for correct answer

Give the number of valence electrons for CH₂Cl₂.

16

12

18

20

22

Answer: 20

C = 4
H = 1
Cl = 7

1×4 + 2×1 + 2×7 = 20 valence electrons

Give the number of valence electrons for XeI₂.

22

18

24

16

20

Answer: 22

Xe = 8
I = 7

1×8 + 2×7 = 22 valence electrons

Give the number of valence electrons for ICl5.

36

40

44

46

42

Answer: 42

Explanation:
I = 7
Cl = 7

1×7 + 5×7 = 42 valence electrons

Choose the best Lewis structure for NH₄⁺
See attached image for answer choices

Answer: see attached image for correct answer

Explanation:
when a compound is positively charged we subtract 1 from the total electron count. This allows us to form an octet by subtracting 1 from nitrogen in this case.

Identify the number of bonding pairs and lone pairs of electrons in Br₂.

2 bonding pairs and 1 lone pair

4 bonding pair and 2 lone pairs

2 bonding pairs and 3 lone pairs

6 bonding pair and 1 lone pair

1 bonding pairs and 6 lone pairs

Answer: 1 bonding pairs and 6 lone pairs

Explanation:
a bonding pair is a connection between the elements in a molecule. An electron pair is the count of bonding pairs + the count of lone pairs.

Draw a Lewis structure for the following molecule.
NF₃

Answer: see attached image

explanation:
NF3 has 26 valence electrons since nitrogen atoms have 5 valence electrons and fluorine atoms have 7 valence electrons.  Connecting the nitrogen atom to each fluorine atom with a single bond and then distributing the remaining 20 electrons as lone pairs across the atoms allows for each atom to have a completed octet

Draw a Lewis structure for the following molecule.
HBr

Answer: see attached image

Explanation:
Hydrogen has a valence shell that can only hold two electrons. Since a H atom has one electron, it only needs one more to complete its shell. However, bromine has seven valence electrons and only needs one to complete its octet. Thus, in HBr bromine and hydrogen share a single electron pair to satisfy both of their valence shells. The remaining six electrons exist as lone pairs on the Br atom.

Draw a Lewis structure for the following molecule.
SBr₂

Answer: see attached image

Explanation:
The sulfur shares a single electron pair with each bromine atom to satisfy the octet rule. Although sulfur can have an expanded octet, the most stable and likely conformation is the formation of a single covalent bond between the sulfur atom and each bromine atom. The remaining electrons exist as lone pairs on each atom.

Draw a Lewis structure for the following molecule.
CCl₄

Answer: see attached image

explanation:
Carbon has enough valence electrons (four) to share one electron with each chlorine atom to complete the octets of all five atoms in CCl4. In the correct Lewis structure, carbon shares a pair of electrons with each chlorine atom to form four covalent bonds, and the remaining 24 electrons exist as lone pairs on the chlorine atoms.

Write a Lewis structure for the molecule or ion.
N₂H₂

Answer: see attached image

Explanation: Each nitrogen atom contributes 5 valence electrons, and each hydrogen atom contributes 1. The correct structure of this molecule utilizes 12 valence electrons and allows each nitrogen atom to have a full octet of electrons (bonding and nonbonding) while minimizing the formal charge. A double bond between nitrogen atoms allows for every atom to have a formal charge of 0.

Write a Lewis structure for the molecule or ion.
N₂H₄

Answer: see attached image:

Explanation:
The total number of valence electrons is 14 (5 from each nitrogen atom and 1 from each hydrogen atom). Each atom has a full octet (or duet in the case of hydrogen). Elements in the second period are unable to have expanded octets because there are only four orbitals at the valence level (n=2).

Write a Lewis structure for the molecule or ion.
C₂H₂

Answer: see attached image

Explanation:

Carbon can form up to four single bonds, but, when bonded with fewer atoms, a triple bond is possible.

Write a Lewis structure for the molecule or ion.
C₂H₄

Answer: see attached image

Explanation:
Carbon can form single bonds, double bonds, and triple bonds as long as the octet rule is satisfied.

How many lone pairs of electrons are on the As atom in AsF₃?

0

1

2

3

Answer: 1

Explanation: draw the lewis structure for the compound and then identify which

Which element can expand its valence shell to accommodate more than eight electrons?

He

O

P

C

Answer: P (phosphorus)

Explanation: Because phosphorus is a third row element, it can be expanded to accommodate more than eight electrons (has access to 3d orbitals)

Which of the following contains an atom that does not obey the octet rule?

NaCl

BrF

BrF₃

SiO₂

Answer: BrF₃

Explanation: Draw the lewis structures for each and determine if it is an octet or not

NaCl - ionic bonding meaning electrons are transferred NOT shared
metal + nonmetal = ionic bond
Na⁺ Bonds with Cl^- to create octet

BrF - covalent bonding (two nonmetals) electrons shared
Br shares one electron with flourine, Flourine shares one electron with Br
This creates an octet for each of the elements

BrF₃ - covalent bonding electrons shared
Br forms 3 covalent bonds with 3 Fs
This means there are 2 lone pairs
Total electrons around Br = 6 bonding electrons + 4 nonbonding electrons = 10 electrons around Br
This violates octet rule which needs 8 electrons around Br (expanded octet is possible because its a 3rd row element those elements on rows 3+ can expand octet while those on rows 1 or 2 cannot

SiO₂ - Si forms double bonds with O to obey octet rule

Choose the best Lewis structure for XeI2.

See attached image for correct answer

Choose the best lewis structure for ICl₅

See attached image for correct answer

Choose the best Lewis structure for SF₄.

Answer shown in attached image

Note the answer does not reflect the exact form of the correct answer but structurally it is the same

Choose the best Lewis structure for BF₃

Asnwer shown in attached image

Which compound has the longest carbon-carbon bond length?

CH2CH2

HCCH

CH3CH3

all bond lengths are the same

Answer: 

explanation: 
Single bonds are longest
Double bonds are shorter
Triple bonds are even shorter


CH₂H₂:  contains a double carbon-carbon bond
     H H

      \ /

C = C

/ \

H H

HCCH: contains a triple carbon-carbon bond
H – C ≡ C – H

CH₃CH₃: contains a single carbon-carbon bond
     H H

      \ /

H – C – C – H

              / \

             H H

Therefore CH₃CH₃ has the longest carbon-carbon bond length

Place the following in order of increasing bond length.

C-F, C-S, C-Cl

C-S < C-Cl < C-F

C-F < C-S < C-Cl

C-S < C-F < C-Cl

C-Cl < C-F < C-S

C-F < C-Cl < C-S

Answer: C-F < C-Cl < C-S

Explanation:
Bond length is influenced by:

Atomic radius — larger atoms form longer bonds

Bond order — more bonds (e.g., double/triple) = shorter bond (not relevant here since all are single bonds)

Electronegativity and orbital overlap — more effective overlap = shorter bond

Therefore, we can identify the longest bond length for this question by finding the element with the largest atomic radius (use attached image for reference)

F < Cl < S

Give the approximate bond angle for a molecule with an octahedral shape.

120°

180°

90°, 180°

109.5°

105°

Answer: 90°, 180°

explanation:
You need to memorize the table attached.
Octahedral meaning 6 electron groups

Know the angle associated with the geometric shape

90° between atoms in adjacent positions

180° between atoms directly opposite each other (linear across the central atom)

Determine the electron geometry (eg) and molecular geometry (mg) of CH3⁺¹.

eg=tetrahedral, mg=trigonal pyramidal

eg=trigonal planar, mg=bent

eg=tetrahedral, mg=trigonal planar

eg=trigonal planar, mg=trigonal planar

eg=tetrahedral, mg=tetrahedral

Answer: eg=trigonal planar, mg=trigonal planar

Explanation: draw lewis structure

C = 4
H = 1 × 3 = 3 total

Because it is positively ionized we subtract 1 from sum total valence meaning 6 total valence

   H
    |
   C
  /   \
H    H

Normally C woudl have 4 valence but positively charged so lose an  electron

3 EG, 3 BG , 0 LP

Points to trig planar and trig planar for EG and BG (see attached table)

Determine the electron geometry (eg) and molecular geometry (mg) of SiF4.

eg=trigonal bipyramidal, mg=trigonal pyramidal

eg=tetrahedral, mg=tetrahedral

eg=tetrahedral, mg=bent

eg=octahedral, mg=square planar

eg=tetrahedral, mg=trigonal pyramidal

Answer:eg=tetrahedral, mg=tetrahedral

explanation:

Draw lewis structure
Determine EG, BG, and LP
Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of PF₅.

eg=trigonal bipyramidal, mg=trigonal bipyramidal

eg=octahedral, mg=octahedral

eg=trigonal planar, mg=octahedral

eg=trigonal bipyramidal, mg=tetrahedral

eg=tetrahedral, mg=trigonal pyramidal

Answer: eg=trigonal bipyramidal, mg=trigonal bipyramidal

Explanation:

Draw lewis structure
Determine EG, BG, and LP
Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of CO2.

eg=trigonal planar, mg=trigonal planar

eg=linear, mg=linear

eg=linear, mg=trigonal planar

eg=trigonal planar, mg=bent

eg=tetrahedral, mg=tetrahedral

Answer: eg=linear, mg=linear

Explanation:

Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of the underlined carbon in CH3CN.

eg = linear, mg = bent

eg = bent, mg = tetrahedral

eg = linear, mg = linear

eg = tetrahedral, mg = bent

eg = trigonal planar, mg = tetrahedral

Answer: eg = linear, mg = linear

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry of underlined carbon with VESPR table

When a central atom has an expanded octet, what geometric shape might the species exhibit?

Hint: An expanded octet would require more than four electron pairs around the central atom.

Equatorial

Trigonal planar

Tetrahedral

Seesaw

Answer: Seesaw

Explanation:
Equatorial - not even a geometry
Trigonal planar - involves 3 electron groups
Tetrahedral - involves 4 electron groups
Seesaw - involves 5 electron groups

Since seesaw is the only option with electron groups > 4 it is the correct answer

According to VSEPR theory, what determines the geometry of a molecule?

the repulsions between electron groups on interior atoms of a molecule

the repulsions between electron groups and the nucleus of an interior atom in a molecule

the attractions between electron groups and the nucleus of an interior atom in a molecule

the attractions between electron groups on interior atoms of a molecule

Answer:
the repulsions between electron groups on interior atoms of a molecule

Explanation:
this is a definition

The bond angle in NH3 is

120°

104.5°

109.5°

107°

95°

Answer:

ExplanationIdeal tetrahedral angle = 109.5°

Lone pairs repel more strongly than bonding pairs, so they compress the bond angle slightly.

Draw the Lewis structure of H2O. Include any nonbonding electron pairs.

What is the electron geometry of H2O?

Answer: See attached image
Electron geometry = tetrahedral because there are 4 electron groups

What is the electron geometry of SBr4?

Answer: trigonal bipyramidal

Explanation: It has 5 electron groups

What is the electron geometry of BI3?

Answer: trigonal planar

Explanation it has 3 electron groups

Determine the electron geometry (eg) and molecular geometry (mg) of BCl3.

eg=tetrahedral, mg=trigonal pyramidal

eg=tetrahedral, mg=trigonal planar

eg=trigonal planar, mg=bent

eg=trigonal bipyramidal, mg= trigonal bipyramidal

eg=trigonal planar, mg=trigonal planar

Answer: eg=trigonal planar, mg=trigonal planar

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of NCl3.

eg=tetrahedral, mg=trigonal pyramidal

eg=tetrahedral, mg=tetrahedral

eg=linear, mg=trigonal planar

eg=linear, mg=linear

eg=trigonal planar, mg=bent

Answer: eg=tetrahedral, mg=trigonal pyramidal

explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of ICl2-.

eg=tetrahedral, mg=trigonal pyramidal

eg=octahedral, mg=linear

eg=trigonal bipyramidal, mg=linear

eg=trigonal bipyramidal, mg=trigonal planar

eg=tetrahedral, mg=bent

Answer: eg=trigonal bipyramidal, mg=linear

explanation: 
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of XeF2.

eg=tetrahedral, mg=linear

eg=tetrahedral, mg=bent

eg=trigonal bipyramidal, mg=linear

eg=linear, mg=linear

eg=trigonal bipyramidal, mg=bent

Answer:eg=trigonal bipyramidal, mg=linear

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of XeF4.

eg=tetrahedral, mg=bent

eg=linear, eg=linear

eg=tetrahedral, mg=tetrahedral

eg=octahedral, mg=square planar

eg=trigonal bipyramidal, mg=tetrahedral

Answer: eg=octahedral, mg=square planar

explanation:

Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of the underlined atom CH3OCH3.

eg=tetrahedral, mg=bent

eg=tetrahedral, mg=tetrahedral

eg=trigonal bipyramidal, mg=tetrahedral

eg=linear, eg=linear

eg=octahedral, mg=square planar

Answer: eg=tetrahedral, mg=bent

explanation:

Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

Determine the electron geometry (eg) and molecular geometry (mg) of the underlined atom H2CO.

eg=trigonal bipyramidal, mg=tetrahedral

eg=trigonal planar, eg=trigonal planar

eg=tetrahedral, mg=tetrahedral

eg=octahedral, mg=square planar

eg=tetrahedral, mg=bent

Answer: eg=trigonal planar, eg=trigonal planar

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

What is molecular geometry of XeF4?

Octahedral

Seesaw

Square planar

Tetrahedral

Answer: Square planar

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

How many of the following molecules are polar?

PCl5, COS, XeO3, SeBr2

2

1

3

4

0

Answer: 3


explanation:
use geometry to 
PCl5 is nonpolar
COS is polar
XeO3 is polar
SeBr2 is polar

Determine the electron geometry (eg), molecular geometry (mg), and polarity of SO2.

eg=linear, mg=linear, nonpolar

eg=tetrahedral, mg=tetrahedral, nonpolar

eg=tetrahedral, mg=bent, polar

eg=trigonal planar, mg=bent, polar

eg=trigonal pyramidal, mg=trigonal pyramidal, polar

Answer: eg=trigonal planar, mg=bent, polar

Explanation:
Draw lewis structure

Determine EG, BG, and LP

Then determine geometry with VESPR table

use geometry and bond angles to determine polarity