Monday, May 16, 2011

New Chemical Bonds that will Blow Your Mind!!!!

Recently in Ms. Chen's class, we have learned new types of chemical bonds that I have never dealt with before! They are:

  1. Non Polar Covalent Bonds: if electrons are shared equally
  2. Covalent Bonds: if electrons are shared unequally
  3. Ionic Bonds: if the electrons are transferred between 2 atoms
Before I get into explaining, let's review the basics of Electrostatic Force:
Electrostatic Force is a force that exists between charged particles as a result of attraction/repulsion. This operates equally in all directions.
  • Opposite charges attract
  • Like charges repel
  • The greater the distance between two charged particles, the smaller the attractive force
  • The greater charge on the particles, the greater the force of attraction

Typically, atoms with higher electro negativity strongly attract electrons from neighboring atoms. 

The trends for Electronegativity are the same as the trends for Ionization.
This is because, metals have low electronegativity and non metals have high electronegativity resulting in high ionization energies

You can measure electronegativity using the "Pauling Scale"
Electronegativity Difference = [Energy1 - Energy2]
1) IF ENeg Diff. < 0.5 it is a COVALENT BOND
2) IF ENeg Diff. > 0.5 and < 1.8 it is a POLAR COVALENT BOND
3) IF ENeg Diff. > 1.8 it is an IONIC BOND

NOW we will move on to intermolecular forces. These hold together individual molecules containing intramolecular covalent bonds forming covalent compounds.

How to differentiate between the two?
INTRAmolecular forces are found within a molecule, responsible for holding the atoms of a molecule together
INTERmolecular forces are found between the molecules, responsible for the bonding between molecules

Now you may ask, why do some bonds have low melting points? Well the answer to that question is simply because of weak bonds
                - During the melting process, only the weak bonds are affected. The covalent bonds 
                  within each individual molecule are not broken.
The LONDON FORCES are the weakest intermolecular force. This is due to temporary dipolar attractions between neighbouring atoms

A dipole is a partial separation of charge, existing when one end of a molecule has a slight positive charge and the other end has a slight negative charge

 > Outlines a molecule's electrical balance
 > If there is an imbalance with electrical charge, then the molecule is polar, if it is balanced, it is 
    non polar

Atoms with Higher Electronegativity will form a PARTIAL NEGATIVE charge
δ- (between 0 and -1)
Atoms with Lower Electronegativity will form a PARTIAL POSITIVE charge
δ+(between 0 and +1)

Example: NH3
N: 3.04
H: 2.20

3.04-2.20 = 0.84 meaning it is a polar covalent bond

Here are videos to sum up everything in this blog: 

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