Ionic and Covalent Compounds

Ionic compounds consist of two or more ions which are held together by ionic bonds. These particles are oppositely charged; the particles which are positively charged are including metal cations, and the particles that are negatively charged are includes anions, or the polyatomic ion. Through the oppositely charged particles, they stick together by electrostatic force. The transfer of electrons always occurs between a metal to a non-metal. Generally, ionic compounds have similar properties; a high melting and boiling point, and being hard and brittle.

Ex. W (+6) & F (-1)
The charges of the positive and negative ion have to be able to cancel out. Therefore, you need 6 F’s in order to satisfy the equation. So the result is:

Ex. WF₆ (Tungsten fluoride)

Also, when you name an ionic compound, the metal always comes before the non-metal.

Ex. Cu (+2 or +1) & S (-2)

Cu2S (Copper (I) Sulphide)

Sometimes there are more than one charge on the ion, and depending on the formula given and the situation, (I), (II) etc… show us what the charge is on the ion.

What are complex anions? Complex anions actually aren’t complex at all; they are just a group of atom that are already combined, which acts as one atom. They are negative particles that are made up of combined gases. For example, chlorate (Clo3-).

Ex. Combine Potassium and Acetate

K(+1) is potassium and CH3COO (-) is Acetate, and since the charges will cancel, the result is simply:

KCH3COO

Now, on to covalent compounds; covalent compounds are essentially the opposite of an ionic compound, instead of transferring electrons, they share them. The two elements in the covalent compound should be both non-metal’s.

To name or to write formula’s of covalent compounds, you need to know your diatomic molecules. They consist of two atoms, and to name it you need to know your prefixes.

The diatomic molecules are: H2, 02, F2, Br2, I2, N2, and Cl2. An easier way to memorize this is to remember the HOFBrINCl, or the Magnificent Seven (the elements are in a shape of a 7 on the periodic table).

The prefixes you should have memorized are :

mono- 1 tetra- 4 hepta- 7 deca- 10
di- 2 penta- 5 octa- 8
tri- 3 hexa- 6 nona- 9

When you name covalent compounds, the first element stays the same. However, with the second element, you add the prefix to the beginning, then change the last part of the element to "ide". Also, if the prefix and the element both have a vowel, cancel out the vowel from the prefix. For example, instead of it being tetraoxide, it'd be tetroxide.

Ex. NI3

N being Nitrogen, and I is Iodide. The prefix for 3 is tri, therefore the result would be:

Nitrogen triodide

For more information on this , go to these links :
http://misterguch.brinkster.net/ionic.html
http://misterguch.brinkster.net/covalentcompounds.html
http://en.wikipedia.org/wiki/Diatomic_molecule