Bonds in Chemistry

When thinking about molecules and the arrangement of atoms their is quite a lot more to understand than just thinking that a molecule has bonds or atoms are bonded to each other. To understand the way that atoms bond to each other we must take into account the protons, neutrons and electrons that are present within the atom.

Water the most abundant compound on this planet, water covers around 70.9% of the earths surface ( http://en.wikipedia.org/wiki/Water ). Without water life would not be possible, water is unique it is able to exist as all three states being solid, liquid and gas. Water also is the only compound where its solid state is able to float on top of its liquid state, as with most solids they should sink but ice being the solid state of water floats this is all due to the bonding that is present with in water. At 0 degree liquid water will freeze into ice its solid state, at 100 degrees water will boil and form steam thus is present in its gaseous form.

picture from - http://www.freedigitalphotos.net/images/view_photog.php?photogid=1977 

If you could remember back to your time at school if you payed attention in your science classes that is you would remember the questions the teachers gave us on solids, liquids and gases. A compound that is solid has its particles knitted so closely together, a liquid even further apart and finally in a gas the molecules seemed so far apart you could only draw one or two molecules in the little box they provided you with in a exam.

Bonding in chemistry

Covalent

A water molecule has the chemical symbol of H20, meaning it is made up of two hydrogen atoms and one oxygen atom. If you read my article on atoms it may help you understand the electron paring in bonding chemistry. The oxygen atom is in group 6 of the periodic table it has 6 outer electrons in its outer most shell, hydrogen has 1 electron in its outer most shell in need of one extra electron. By the oxygen sharing two of its electrons with two hydrogen’s and the hydrogen’s sharing each of their spare electrons all three atoms have a shared full of outer electrons. This type of bonding is known a covalent bonding (the sharing of electrons). 

A simple analogy, 2 friends at a cafe wanting to buy a cheeseburger, which costs £1 they each have 50pence, they decide to put there money together to make up that pound so they can both equally share the cheeseburger. Its a very simple analogy of what really is going on in covalent bonding.

 Dative covalent

To understand dative covalent bonding, its best to look at it as the most generous form of bonding, in this type of bonding both electrons are supplied by one atom only.

Ionic bonding 

The best way to understand ionic bonding is by first to realise that the bond its self is the result of electrostatic attraction between two oppositely charged Ions. this type of bonding is seen normally with a metal and non-metal, the metal is the atom which donates its electron or electrons to the non-metal, due to the loss of a negative charge the atom becomes a positive ion (there are more protons in the atom than there is now electrons meaning there is a greater positive charged exerted by the atom, thus turning it into a positive ion). Please read section on the atom if unclear about the charges in atoms.

The metal has lost electrons becoming a positively charged ion also known as a cation.

The non-metal accepting the electrons is now more negatively charged thus becoming a negatively charged ion known as an anion.

It is these opposite charges created by the transfer of electrons that an electrostatic force is created between the two, thus becoming an ionic bond.

The transfer of electrons is done so that the metal and non-metal would have a full outer shell of electrons.