Covalent Bonding Part 2

Open Ended

Why is understanding molecular structure, shape, and polarity important in chemistry?

Multiple Choice

Which of the following statements about Lewis Structures is correct?

• Lewis Structures use elemental symbols and bonds to show the relative position of the atoms.

• Lewis Structures use numbers to represent electrons.

• Lewis Structures do not show nonbonding electrons.

• Lewis Structures only use dashes to represent electrons.

Multiple Choice

What is the first step in drawing Lewis structures for molecules or ions?

• Sum the valence electrons from all atoms

• Decide which atom is the central atom

• Complete the octet of all atoms

• Count the number of electrons surrounding the central atom

Multiple Choice

According to the rules for drawing Lewis structures, which atom is NEVER the central atom?

• Hydrogen

• Carbon

• Oxygen

• Chlorine

Open Ended

Explain why hydrogen follows the duet rule instead of the octet rule when drawing Lewis structures.

Multiple Choice

When drawing Lewis structures, what should you do if the central atom does not have an octet after all electrons have been placed?

• Form multiple bonds using nonbonding electron pairs

• Remove electrons from the central atom

• Add more atoms to the molecule

• Ignore the octet rule

Open Ended

Based on the example of CH2O, describe the process for determining the central atom and connecting the atoms with single bonds in a Lewis structure.

Multiple Choice

Which atom in the CH2O molecule is the central atom when drawing its Lewis structure?

• Carbon

• Oxygen

• Hydrogen

• Nitrogen

Multiple Select

Which of the following statements are true about the octet rule as applied in the CH2O Lewis structure process?

• Hydrogen can only have two electrons.

• The central atom must satisfy the octet rule.

• Lone pairs are added to all atoms except the central atom.

• Leftover electrons are placed on the central atom.

Open Ended

Explain why it is sometimes necessary to form double or triple bonds in a Lewis structure, using CH2O as an example.

Multiple Choice

What information does the Lewis structure of a molecule provide that the molecular formula does not?

• The number of atoms involved

• The types of atoms present

• The connectivity and arrangement of atoms

• The molecular mass

Multiple Choice

How many valence electrons are present in a C2H2 molecule?

• 8

• 10

• 12

• 14

Multiple Choice

Which of the following statements best describes resonance structures?

• They differ only in the position of the electron pairs and multiple bonds, never the position of the atoms.

• They differ in the number of atoms present in the molecule.

• They differ in the types of atoms present in the molecule.

• They differ in the total number of electrons in the molecule.

Open Ended

Explain why the carbonate ion (CO3 2-) has more than one resonance structure. What does this indicate about the bonding in the ion?

Multiple Choice

Which molecule is used as an example of a molecule with less than an octet in the lesson?

• BF3

• SF6

• NO

• CO3 2-

Multiple Select

Which of the following molecules are exceptions to the octet rule?

• BF3

• NO

• SF6

• CH4

Multiple Choice

What is the main limitation of Lewis structures as described in the lesson?

• They do not indicate the shapes of molecules.

• They cannot show the number of bonds.

• They cannot show the types of atoms.

• They do not show electron pairs.

Multiple Choice

According to the VSEPR model, what determines the geometric arrangement of atoms in a molecule?

• The repulsions between electron pairs around a central atom

• The atomic mass of the central atom

• The number of protons in the nucleus

• The temperature of the environment

Multiple Choice

How does the VSEPR model help predict the shape of a molecule?

• By considering the electrostatic repulsions between bonding and nonbonding electron pairs

• By measuring the atomic radius of the central atom

• By counting the number of atoms in the molecule

• By analyzing the color of the atoms

Open Ended

Compare the molecular geometries and bond angles of beryllium chloride and boron trifluoride as shown in the images.

Multiple Choice

Which of the following molecules has a tetrahedral molecular geometry?

• Methane

• Beryllium chloride

• Boron trifluoride

• Phosphorus pentachloride

Multiple Select

Select all the correct bond angles present in phosphorus pentachloride according to the VSEPR model.

• 90°

• 109.5°

• 120°

• 180°

Open Ended

How do you think understanding molecular structure and Lewis dot structures can help you predict the properties of a molecule?

Multiple Choice

What is the purpose of using dots and dashes in Lewis structures?

• Dots represent bonding electrons, dashes represent nonbonding electrons.

• Dots represent nonbonding electrons, dashes represent a pair of bonding electrons.

• Dots represent atoms, dashes represent molecules.

• Dots represent protons, dashes represent neutrons.