Note: this is intended to be as simple and easy to understand as possible. However, it is quite complex chemistry if you don't quite understand something try reading it again or you can email me any questions you have.
To understand how atoms a combine and why they combine you must first must understand what they are made of…
Atoms consist of three main particles – Protons, neutrons and electrons. The electrons are the particle which is concerned in all three types of bonding. The diagram below shows this:
Notice in the diagram that the electron (blue) has a negative sign, the proton (red) has a positive sign and the neutron (green) has no sign. This is referring to its charge. For example one electron can be said as being 1- and a proton 1+. Therefore, two electrons could be written as having a charge of 2- and so on.
The three main types of bonding are shown below:
1. Ionic Bonding
2. Covalent bonding
3. Metallic Bonding
I will go through each individually:
1. Ionic bonding.
In brief, ionic bonding is the transfer of electrons from one atom to another. It is a bond between metals and non-metals and forms what is called an ionic lattice.
Note: the aim of all atoms is to have the same number of outer electrons as the group 0 (red on table below) which is 8. The number of outer electrons equals the group number (before an element bonding).
To determine how many electrons are gained or lost you need to look at the periodic table below.
If an element were in groups 1-3 it would lose the same number of electrons as is its group number. Hence becoming positively charged because electrons are negative and you are left with more positive protons than negative electrons.
However, if an element is in groups 5-7 it would take electrons from the ones which we giving them up to become negative - Hence getting 8 outer electrons.
An ionic substance forms into large structures called lattices. As shown below:
On the above diagram the yellows are positive and the blues are negatively charged. They compound stays together as positive is attracted to negative.
Properties
· High melting and boiling points
· Conducts electricity
1.Covalent Bonding
Covalent bonding is very different from ionic bonding as it involves only non-metals and is the sharing of electrons as opposed to the transfer of them.
A covalent bond is defined as the sharing of electrons to achieve a stable outer electron arrangement. The bond is held together by the forces of attraction between the positive and negative charges. They are very hard to break and therefore require large amounts of energy to break (1000 KJ mol-1 to be exact)
There are two types of covalent bonding that I will explain separately:
2.1 Covalent molecular
1.2 Covalent network
2.1 The covalent molecular bond is formed between non-metal elements to form compounds. A covalent molecular substance consist of a small molecules joined together by strong covalent bonds and the other molecules in the substance are held together with weak forces called Van Der Waal's (pronounced van-der-val) forces. The diagram below shows this in action in water:
The solid lines between the circles represent the covalent bonds and the dotted lines represent the weak Van Der Waal forces.
Properties
· Does not conduct electricity
· Very low melting and boiling points
2.2 The covalent molecular molecule is the same except everything is joined by covalent bonds and there are no weak forces involved. They form giant structures. A human is mainly a giant covalent structure of carbon.
Properties
· Very high melting and boiling points
· Does not conduct electricity (except from carbon in the form of graphite)
2. Metallic Bonding
Metallic bonding is the sharing of free electrons (delocalised electrons) they form lattice structures very similar to that of ionic compounds.
Properties
· Conducts electricity
· High Melting and boiling points
Connor Davidson 05/05/09
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