LT#4: VSEPR Theory & Polarity

Question 1

When drawing Lewis diagrams, how do you adjust for a charged molecule?

Answer 1

Add valence electrons to get a negative charge, remove to get positive.

Question 2

Define Resonance Structure?

Answer 2

A molecule with 1.5 bonds.

Double bond electrons are delocalized and shared around the molecule.

Question 3

How do you recognize a resonance structure?

Answer 3

Molecules need a double bond, but there is more than one possible place for it.

You must draw all possibilities separated by double headed arrows.

Question 4

Define an Expanded Valence Molecule

Answer 4

Contains atoms with more than 8 electrons.

Question 5

How do you recognize an Expanded Valence Molecule?

Answer 5

If you need more bonds to hold your molecule together than calculated.

Question 6

How do you complete an Expanded Valence Molecule diagram?

Answer 6

Stop doing the method and add lone pairs until you have placed all your valence electrons on your diagram (don’t forget to include the 2 electrons in each bond when counting).

Start by making the outside atoms stable, and then add any extra lone pairs to the central atom.

Question 7

Name the electron arrangement with 2 electron groups

Answer 7

Linear

Question 8

Name the electron arrangement with 3 electron groups

Answer 8

Trigonal Planar

Question 9

Name the electron arrangement with 4 electron groups

Answer 9

Tetrahedral

Question 10

Name the electron arrangement with 5 electron groups

Answer 10

Trigonal Bipyramidal

Question 11

Name the electron arrangement with 6 electron groups

Answer 11

Octahedral

Question 12

What are the bond angles in a linear arrangement?

Answer 12

180

Question 13

What are the bond angles in a Trigonal Planar arrangement?

Answer 13

120

Question 14

What are the bond angles in a Tetrahedral arrangement?

Answer 14

109

Question 15

What are the bond angles in a Trigonal Bipyramidal arrangement?

Answer 15

90, 120, 180

Question 16

What are the bond angles in an Ocahedral arrangement?

Answer 16

90, 180

Question 17

What possible molecular shapes can be created with a linear arrangement?

Answer 17

Linear

Question 18

What possible molecular shapes can be created with a Trigonal Planar arrangement?

Answer 18

Trigonal Planar (no LP’s)

Bent 120 (1 LP)

Question 19

What possible molecular shapes can be created with a Tetrahedral arrangement?

Answer 19

Tetrahedral (no LP’s)

Trigonal Pyramidal (1 LP)

Bent 109 (2 LP’s)

Question 20

What possible molecular shapes can be created with a Trigonal Bipyramidal arrangement?

Answer 20

Trigonal Bipyramidal (no LP’s)

Seesaw (1 LP)

T-shape (2 LP’s)

Linear (3 LP’s)

Question 21

What possible molecular shapes can be created with an Octahedral arrangement?

Answer 21

Octahedral (no LP’s)

Square Pyramidal (1 LP)

Square Planar (2 LP’s)

Question 22

Define Polar Compound

Answer 22

A polar compound or dipole has polar covalent bonds and a shape that result in a charge imbalance.

Question 23

Define Non-polar Compound

Answer 23

Non–Polar compounds have non-polar covalent or polar covalent bonds that counteract each other

Question 24

How do you recognize a Polar Compound?

Answer 24

Asymmetrical shape OR different atoms on the arms

Question 25

How do you recognize a Non-polar Compound?

Answer 25

Must have symmetrical shape AND the same atoms on the arms