In ionic bonding atoms lose or gain
electrons to form charged particles (called
ions) which are then strongly attracted to one
another (because of the opposite charges
A shell with just one electron is keen to get rid..
All the atoms over at the left hand side of the periodic table
e.g. calcium etc have just one or two electrons in their outer
shell (highest energy level). They are keen to get rid of
them because then theyll have full shells left. (They try to
have the same electronic structure as a noble gas.) That
leaves the atom as an ion instead. They leap at the first
passing ion with an opposite charge and stick to it like glue.
A nearly full shell is keen to get that extra electron
On the other side of the periodic table the elements in group 6 and 7 e.g.
oxygen etc have outer shells that are nearly full. They are obviously keen
to gain that extra one or two electrons to fill up the shell up. When they do
of course they become ions they have latched onto the atom (ion) that
gave up the electron earlier.
Ionic compounds have a regular lattice
structure
Ionic compounds always have a giant ionic lattice
There are very strong electrostatic forces of
attraction between oppositely charged ions in all
directions
A single crystal of sodium chloride is one giant ionic
lattice which is why salt crystals tend to be cuboid in
shape. The Na+ and Cl- are held together in a regular
lattice
Ionic compounds all have similar properties
High melting points
High boiling points due to
strong attraction between
the ions
Takes a large amount of energy to overcome this
attraction. When they melt the ions are free to move and
they will carry electric current
dissolve easily. The ions separate and
are all free to move in the solution
Ions and Formulas
Groups 1+2 and 6+7 are most likely to form ions
The atoms that have been lost or
gained an electron are ions
Ions have the electronic structure of a noble gas
Group 1 + 2 are metals and
they lose electrons to form
positive ions
E.g. Group 1 element (alkali metals) form ionic
compounds with non-metals
Group 6+ 7 elements are non-metals. They
gain electrons to form negative ions
E.g. Group 7 elements (halogens) form ionic
compounds with the alkali metals where the halide ion
has a negative charge
The charge on the
positive ions is the same
as the group number of
the element
Any of the positive ions above can
combine with any negative ions to form an
ionic compound
Look at charges to work out the formula of an ionic compound
Ionic compounds are made up of a
positively charged part and a
negatively charged part