LT#4: VSEPR Theory & Polarity Flashcards
When drawing Lewis diagrams, how do you adjust for a charged molecule?
Add valence electrons to get a negative charge, remove to get positive.
Define Resonance Structure?
A molecule with 1.5 bonds.
Double bond electrons are delocalized and shared around the molecule.
How do you recognize a resonance structure?
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.
Define an Expanded Valence Molecule
Contains atoms with more than 8 electrons.
How do you recognize an Expanded Valence Molecule?
If you need more bonds to hold your molecule together than calculated.
How do you complete an Expanded Valence Molecule diagram?
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.
Name the electron arrangement with 2 electron groups
Linear
Name the electron arrangement with 3 electron groups
Trigonal Planar
Name the electron arrangement with 4 electron groups
Tetrahedral
Name the electron arrangement with 5 electron groups
Trigonal Bipyramidal
Name the electron arrangement with 6 electron groups
Octahedral
What are the bond angles in a linear arrangement?
180
What are the bond angles in a Trigonal Planar arrangement?
120
What are the bond angles in a Tetrahedral arrangement?
109
What are the bond angles in a Trigonal Bipyramidal arrangement?
90, 120, 180
What are the bond angles in an Ocahedral arrangement?
90, 180
What possible molecular shapes can be created with a linear arrangement?
Linear
What possible molecular shapes can be created with a Trigonal Planar arrangement?
Trigonal Planar (no LP’s)
Bent 120 (1 LP)
What possible molecular shapes can be created with a Tetrahedral arrangement?
Tetrahedral (no LP’s)
Trigonal Pyramidal (1 LP)
Bent 109 (2 LP’s)
What possible molecular shapes can be created with a Trigonal Bipyramidal arrangement?
Trigonal Bipyramidal (no LP’s)
Seesaw (1 LP)
T-shape (2 LP’s)
Linear (3 LP’s)
What possible molecular shapes can be created with an Octahedral arrangement?
Octahedral (no LP’s)
Square Pyramidal (1 LP)
Square Planar (2 LP’s)
Define Polar Compound
A polar compound or dipole has polar covalent bonds and a shape that result in a charge imbalance.
Define Non-polar Compound
Non–Polar compounds have non-polar covalent or polar covalent bonds that counteract each other
How do you recognize a Polar Compound?
Asymmetrical shape OR different atoms on the arms
How do you recognize a Non-polar Compound?
Must have symmetrical shape AND the same atoms on the arms
