MOLECULES Part 3: SHAPES OF MOLECULES
^What to catch from above slide:
VSEPR stands for Valence-Shell Electron Pair Repulsion, meaning the valence electrons repel each other (bond pairs and lone pairs alike). These electron pairs MOVE AND SHAPE THEMSELVES AROUND AN ATOM to minimize repulsions (see below)
Note that we can describe molecular geometries in two ways: ELECTRON-GROUP GEOMETRY & MOLECULAR GEOMETRY (will be discussed later)
^what to catch from above slide:
NH3 and H2O can be drawn and represented in many ways, but pay attention to MOLECULAR GEOMETRY & ELECTRON GROUP GEOMETRY
Electron group geometry: "how many pairs of electrons are surrounding the given atom?" (see below). Its name is solely dependent on how many electron groups are around the atom whether lone pairs or bond pairs!
^Note there are 2 lone pairs and 2 bonds, so in total there are 4 electron groups!
^Note there are 2 bond groups, so in total there are 2 electron groups! (Yes, triple bond counts as one electron group)
^Note there are 3 bond groups around the carbon, so carbon has a total of 3 electron groups (Yes, double bond counts as one electron group); Oxygen has 2 lone pairs and 1 bond group, so oxygen has a total of 3 electron groups as well.
Molecular geometry: the geometry name changes depending on the presence of lone pairs and how many of them there are
^What to catch from above slide:
A = central atom
X = bond pairs
E = lone pairs
^MEMORIZE THIS TABLE FOR THE TEST
^MEMORIZE THIS TABLE FOR THE TEST
^What to catch from above slide:
For all Lewis structures, you must know how to come up with 1) VSEPR notation 2) Electron group geometry AND 3) Molecular geometry
PRACTICE PROBLEMS ON VSEPR SHAPES OF MOLECULES
ANSWER KEY
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