Bonding

There are 3 types of chemical bonds

Ionic bonds: the transfer between 2 atoms to form a positive and negative ion.
Non-polar covalent bonds: equal sharing of electrons
Polar covalent bonding: unequal sharing of electrons



Ionic bonding uses an electrostatic force. That is the force that exists between particles that are charged as a result of attraction or replusion. (remember, opposites attract? Opposite charges attract and like charges repel). These bonds are very strong and have a high melting temperature.

So, I know you guys have a burning question:

Why do things lose valence electrons? This is explained by electronegativity. Metals have low electronegativity and non-metals have high electronegativity, as we learned in the last chapter. The electronegativity decreases to the right across the periodic table. The difference in the electronegativity will determine the electron sharing and determine if it is equally shared or unequally shared.

Here is how to figure that out! This is the formula:

ENeg Diff.= [ENeg1 - ENeg 2]

If it is a non polar covalent bond, the difference will be <0.5
If it is a polar covalent bond, the difference will be >0.5 and <1.8
If it is an ionic bond, the difference is >1.8


If ENeg Diff <0.5 it's a non polar covalent bond

If ENeg Diff > 0.5 and <1.8 it's a polar covalent bond

If ENeg Diff > 1.8 it's an ionic bond




Lets try an example:

Arsenic and Sulfur
Arsenic is 2.18 and Sulfur is 2.58. |2.18-2.58| = 0.40, therefore it is covalent.

Cobalt and Bromine
Cobalt is 1.88 and Bromine is 2.96 |1.88-2.96| = 1.08, therefore it is a polar covalent bond./

To draw diagrams of the compounds, draw the central atom in the middle and distribute the remaining atoms around it. Draw arrows indicating the direction of the polarity. Draw the partial positive and partial negative charges.

Partial Positive sign is the almost 8 but cut-off sign with a +
Partial Negative sign is the same thing but with a -


What is polarity?
Different Kinds of Bonds