Unit 2: Polarity Flashcards
1
Q
Polarity describes…
A
Describes charges in substance
Electron distribution – atomic En
2
Q
2 types of Polarity
A
Two types:
Bond polarity: + and – ends of bond
Molecular polarity: + and – ends of molecule
3
Q
Bond Polarity is caused by
A
Caused by ∆En
Ex: H─F has polarity:
1.9 in favor of F
4
Q
Bond Polarity
Nature of bond depends on….
A
Nature of bond depends on ∆En
∆En < 0.5 nonpolar covalent
- 5 ≤ ∆En ≤ 1.6 polar covalent
- 6 < ∆En < 2.0 polar covalent or ionic
∆En ≥ 2.0 ionic
Note that high oxidation number metals tend to violate; act as covalent (ex Mn7+)
5
Q
Molecular Polarity
For molecular substance…
A
- For molecular substance, symmetry dependent
- Ionic atoms not considered
- For molecule, depends on electron pull
- If higher electron concentration, polar
- Equal electron concentration, nonpolar
6
Q
Molecular Polarity
Distribution of Electrons based on…
A
- Distribution of electrons based on symmetry
- Considers nonbonding pairs vs. bonding
- Considers polar vs. nonpolar bonds
- Considers differing polarities in polar bonds
- Use geometry like VSEPR to explore
7
Q
A
8
Q
A
- Molecular polarity requires bond vector summation
- Bond vectors can either cancel or not
- Unequal vectors will never cancel
- Equal vectors will cancel when directly opposed
- Vectors not directly opposed will not cancel
- Vector direction arises from molecular structure
9
Q
A
10
Q
A
11
Q
A
12
Q
A
13
Q
A
14
Q
A
15
Q
A
