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.