U6L3 - Lecture Notes - Molecular Structures

Multiple Choice

Which molecular model is one of the most useful and it uses letter symbols and bonds to show relative positions of atoms?

• ball-and-stick

• molecular model

• structural formula

• space-filling molecular model

Fill in the Blank

The molecular formula of a molecule can tell you the ____ and ______ of each atom in a molecule.

,

Match

Match the name of the model at left with the letter at right of its representation of phosphorus trihydride (phosphine) in the figure.

• Molecular formula

• Lewis structure

• space-filling model

• structural model

• ball-and-stick

A

B

c

D

E

• A

• B

• c

• D

• E

Fill in the Blank

A Lewis structure will usually require ________ bonds if there are atoms present that do not have full octets after all available electrons have been placed.

Fill in the Blank

The method used for counting the electrons available for bonding is different for an ion than for a neutral molecule. Compared to the number of valence electrons present in the atoms that make up an ion, ____ electrons are present if the ion is negatively charged and ____ are present if the ion is positively charged.

,

Fill in the Blank

Both Lewis structures and __________ ________ use letter symbols and bonds to show the relative positions of atoms.

Reorder

Place the steps used for drawing Lewis structures in the correct order from beginning to end.

• Predict the location of the central atom and hydrogen atoms.

• Determine the number of electrons available for bonding.

• Determine the number of bonding pairs.

• Place the bonding pairs.

• Determine the number or electron pairs remaining.

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Multiple Select

Which statements correctly describe how to draw a Lewis structure?

Multiple select question.

• The atom with the highest group number is usually the central atom.

• Lone pairs of electrons do not need to be included in the structure.

• A Lewis structure includes all the valence electrons in the species.

• A single bond contains two electrons and is represented by a solid line.

Multiple Choice

Why are resonance structures used when drawing the nitrate ion?

• The placement of atoms of elements can change.

• Equivalent structures can be used to represent the ion.

• The number of atoms of elements can change.