Ionic Compounds

Ionic compounds are formed when a metal and a non-metal join together. When sodium metal is dropped into a gas jar of chlorine gas the elements react violently to form a new compound called sodium chloride joined by ionic bonds. To understand how this process works, we must grasp an understanding of what an ion is and what an ionic bond is.

An ion is an atom that has an electric charge and is created when an atom (or a group) gain or loses electrons. (It has an electric charge due to the imbalance and since they need to neutralise each other.)
An ionic bond is a bond that transfers from one and another, resulting in an attraction between oppositely charged ions.
Sodium chloride (NaCl) is a compound of a metal (Sodium) and a non-metal (Chlorine) join together, the sodium being positively charged and the chlorine being negatively charged. In this reaction, Sodium gives electrons to the Chlorine (which turns it into an ion and it turns into Chloride instead of Chlorine). The Sodium becomes positively charged and Chloride becomes negatively charged. As a result, a force of attraction is created between oppositely charged ions and that force of attraction is a … ionic bond!

Here is a picture of the two elements separately.

There are many ionic bonds in an ionic compound such as sodium chloride, arranged in giant grid like structure. Ionic compounds have high melting and boiling points.
Below, you can see the electron transfer to the chloride, causing them both to become ions.

A covalent bond is a chemical bond, between two non metals, that involves sharing pairs of electrons between atoms.
Here is an example.

Four atoms of hydrogen And one carbon atom

And they combine together to create methane.

Four pairs of electrons are shared in a methane molecule (CH4) (crosses)
Each of the bonds represents a shared electron pair, these atoms bond due to the electrostatic attraction between the positive nuclei and the negative electrons shared between them.
The molecule can be shown as with four carbon – hydrogen single covalent bonds.
This shape is known as a tetrahedral shape, the bond angle is 109 degrees.
The atoms within the molecules are held together by very strong covalent bonds. However the attraction between the molecules is very weak so they can be separated very easily.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/ionicrev4.shtml http://skovranscience.weebly.com/uploads/8/5/1/8/8518324/__16.1_ebook.pdf http://www.le.ac.uk/se/centres/sci/selfstudy/atom2.html http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/covalentrev4.shtml GCSE Chemistry exam board: OCR 21st century- C5 page 48 and 48.