Bonding

=Bonding=

There are three main types of bonding we are concerned with (most students can name ionic and covalent and forget about metallic bonding)

If an element is a metal (most of the Periodic Table) then they have **metallic bonding** - just delocalised electrons really which can explain why they are good conductors of electricity etc. Don't forget about this basic type of bonding - some questions really do just expect you to state the obvious.


 * Ionic bonding -** this occurs between **metals** and **non-metals**. Make sure you are familiar with which are which in the Periodic Table and __use__ one if you need to!! Don't rely on guess work.

Essentially atoms are trying to achieve a noble gas configuration - so may gain or lose electrons to do so.

You should easily be able to draw dot / cross diagrams to show the arrangement of electrons in any atom now (using the 2,8,8 rule from GCSE). Metals will lose electrons to achieve a full shell. Non-metals will gain electrons - e.g. fluorine - this has an atomic number of 9. Therefore it has 9 protons (+). If the atom is neutral it therefore must have 9 electrons. According to the 2,8,8 rule these will be arranged as......

To achieve a full shell, fluorine can GAIN one electron. This will give it a -1 charge overall.

If you look at chlorine this also has 7 electrons in it's outer shell, so gains an electron to achieve a full shell, and also has a -1 charge.

Therefore atoms in the same group have the same charge - you will find it helpful at this stage to **lable these onto your Periodic Table** - then make sure you USE it to help you with questions - don't rely on everything in your head.

So if metals want to lose electrons and non-metals gain them, essentially this happens.

Have this idea in your head by all means - but now we are at A-level we draw what happens as a result of this **transfer** of electrons. See this....

So essentially we would just now write a dot-cross diagram for sodium chloride as this...




 * Covalent bonding** - this occurs between **non-metals**. To be fair some people will find this far more challenging to draw. My advice would be practise, practise, practise.

.. We will cover in class strategies for ensuring that you can tackle these questions.

Examples of covalent bonding.