Bond Polarity and Polar Molecules:

When the bonded atoms of an individual bond are identical, the electrons are shared equally between them
We can represent the electron density in a molecule using an electrostatic potential map
- Example: with an H2 molecule, yellow and green regions on the map show that the electron density is evenly distributed
  - Cool colors (blue and purple) how decreasing electron density and warm colors (red and orange) show increasing electron density
A bond in which electrons are shared equally is called a nonpolar covalent bond
What happens if the atoms sharing electrons are NOT identical?
- Example: HF molecule
  - Fluorine attracts shared electrons much more strongly than hydrogen. As a result, the electron density is much greater near the F nucleus
- A bond in which electrons are NOT shared equally is called a polar covalent bond
Electronegativity is defined as the ability of an atom to attract shared electrons of a covalent bond
- Commonly expressed using the Pauling scale, which is a relative scale and has no units
  - The darker the shade, the higher the electronegativity of the element
- We often use electronegativity differences as a guide for categorizing both polarity and bond type
The symbols δ- and δ+ are typically used to indicate regions of high and low electron density in a bond or molecule
- The electron-rich region of a bond is marked with a δ- symbol, while the electron-poor region is marked with a δ+ symbol
- The δ- and δ+ regions of a bond or molecule are often described as indicating partial charges, but it is important to recognize that a shift in electron distribution does not make a species electrically charged overall
- They do not indicate the presence of ions

	Created by Kristen Wislowski about 4 years ago

Notes gathered from the Smartworks homework

Smartworks Notes