Wednesday, 11 April 2012

Atoms-Ionic Bonding

Atoms-Ionic Bonding
There are two main types of bonding, Ionic and Covalent bonding.  When two or more atoms bond they form a compound. The difference between a compound and a mixture is that a compound is chemically bonded whereas a mixture isn’t chemically bonded.  

In Atoms-Introduction we briefly touched about ions. Ions are charged particles.  In ionic bonding, atoms lose or gain electrons to form ions. These ions are then strongly attracted because of the attraction of opposite charges positive and negative. Atoms react because they want a full outer shell of electrons. A common example of ionic bonding is the reaction of sodium and chlorine.  Sodium (Na) has an Atomic number of 11 meaning it has eleven electrons. This means that there is one electron on the outer shell. Chlorine (Cl) has an Atomic number of 17 meaning it has seventeen electrons.  This means that it has seven electrons on the outer shell needing one more to have a full outer shell.  The Sodium atom gives its outer electron to the Chlorine atom. The Sodium atom becomes Na+   ion because there are more protons (positive particles) then electrons (negative particle).  The Chlorine atom has gained an electron making it a Cl- ion because there are more electrons than protons. The ions bond because of the attraction between the charges. 

The ionic compounds formed have giant ionic lattices. The ions form a closely packed regular lattice arrangement.  Furthermore there is a strong intermolecular force in the ionic compound.  This strong intermolecular force gives ionic compounds high melting and boiling points.  When ionic compounds are molten or dissolved in water they will carry electric current because the ions are free to move.  However when ionic compounds are solid they can’t conduct electricity because the ions aren’t free to move.  

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