Unit 7 Exam

Question 1

When one atom contributes both bonding electrons in a single covalent bond, the bond is called a(n) __________:

Answer 1

Coordinate covalent bond

Question 2

The shape of the methane molecule (CH4) is called _______:

Answer 2

Tetrahedral

Question 3

Which elements can form diatomic molecules joined by a single covalent bond?:

Answer 3

Hydrogen and halogens

Question 4

Experimental evidence suggests that the H-C-H bond angles in ethene, C2H4, are ______ degrees:

Answer 4

120

Question 5

A bond that is not symmetrical along the axis between two atomic nuclei is a(n) _____ bond:

Answer 5

Pi

Question 6

How many electrons can occupy a single molecular orbital?:

Answer 6

2

Question 7

According to the VSEPR theory, molecules adjust their shapes to keep _____ as far apart as possible:

Answer 7

electrons

Question 8

What is the shape of a molecule with the formula AB4?

Answer 8

tetrahedral

Question 9

A bond formed between a silicon atom and an oxygen atom is likely to be a(n) _____ bond:

Answer 9

Polar covalent

Question 10

Which of the following diatomic molecules is joined by a double covalent bond?:
     •H2
     •Cl2
     •N2
     •O2

Answer 10

O2

Question 11

Draw the Lewis Structures of the following. Identify their shape, bond angle, polarity, partial charges:
SO3^2-

Answer 11

look in class downloads and docs folder

Question 12

Which of these elements does not exist as a diatomic molecule?:
     •Ar
     •Br
     •I
     •Cl

Answer 12

Ar

Question 13

Which of the following covalent bonds is the most polar?:
     •H-H
     •H-O
     •N-S
     •H-F

Answer 13

N-S

Question 14

What is thought to cause the dispersion forces?:

Answer 14

The movement of electrons

Question 15

What are the weakest attractions between molecules called?:

Answer 15

Dispersion forces, London dispersion forces, and Van Der Waals forces

Question 16

Which of the following concerning carbon tetraiodide is correct?:
     •Tetrahedral, 109.5, nonpolar
     •Tetrahedral, 109.5, polar
     •Trigonal pyramidal, 107, nonpolar
     •Bent, 104.5, nonpolar

Answer 16

Tetrahedral, 109.5, nonpolar

Question 17

What is the shape of a tri-atomic molecule with a triple bond?:

Answer 17

Linear

Question 18

Which of the forces of molecular attraction is the weakest?:

Answer 18

Van der Waals forces

Question 19

What is the name given to pairs of valence electrons that do not participate in bonding in diatomic oxygen molecules?:

Answer 19

Lone pairs

Question 20

How many covalent bonds are in a covalently bonded molecule containing 1 phosphorus atom and 3 chlorine atoms?:

Answer 20

3

Question 21

What is the bond angle in a water molecule?:

Answer 21

104.5

Question 22

Draw the Lewis Structures of the following. Identify their shape, bond angle, polarity, partial charges:
SO3

Answer 22

check class download and docs folder

Question 23

How many unshared pairs of electrons are in a molecule of hydroiodic acid?:

Answer 23

3

Question 24

How many sigma bonds are there in a molecule of carbon dioxide?:

Answer 24

2

Question 25

What is the shape of a molecule of ammonia (NH3)?:

Answer 25

Trigonal pyramidal

Question 26

Which of the following is correct concerning the number of sigma and pi bonds in N2?:

Answer 26

1 sigma, 2 pi

Question 27

What would the bond angle of phosphorus trichloride be?:

Answer 27

107

Question 28

Molecular shape…..Straight line:

Answer 28

molecule made up of only 2 atoms

Question 29

Molecular shape … Linear:

Answer 29

• 2 atoms of opposite sides of central atom, no lone pairs around central atom
• 180º bond angles

Question 30

Molecular shape … Trigonal or Triangular Planar:

Answer 30

• 3 atoms form a triangle around the central atom, no lone pairs around central atom
• Planar
• 120º bond angles

Question 31

Molecular shape … Tetrahedral:

Answer 31

• 4 surrounding atoms form a tetrahedron around the central atom, no lone pairs around the central angle
• 109.5º bond angles

Question 32

Molecular shape … Pyramidal or Trigonal Pyramidal:

Answer 32

• 3 bonding areas and 1 lone pair around the central atom

* Bond angle = 107º

Question 33

Molecular shape … V-shaped or Bent:

Answer 33

• 2 bonding areas and 2 lone pairs around the central atom

* Bond angle = 104.5º