Qrtr 4 final

Metals, with only a few electrons in the outer energy level, tend to lose electrons most readily. The
energy required to remove an electron from a neutral atom is called the IONIZATION POTENTIAL.
Energy + Metal Atom ---> Metal (+) ion + e-
Non-metals, which lack only one or two electrons in the outer energy level have little tendency to lose
electrons - the ionization potential would be very high. Instead non-metals have a tendency to gain
electrons. The ELECTRON AFFINITY is the energy given off by an atom when it gains electrons.
Non-metal Atom + e- --- Non-metal (-) ion + energy
The energy required to produce positive ions (ionization potential) is roughly balanced by the energy
given off to produce negative ions (electron affinity). The energy released by the net force of
attraction by the ions provides the overall stabilizing energy of the compound.
Notes Section:
l. Ionic compunds
Molecules with opposite charges are called ionic. Ionic compounds are generally solid with high melting
points and conduct electricity. These bonds form between metals and non-metals (for example Na and Cl
makes table salt.)
Using the same example of salt, the positive charge of Sodium (Na) and the negative charge of Chlorine
create a neutral bond. They even each other out to get a neutral charge.
It is important to remember that ions are completely different in physical and chemical properties from the
original elements.
The + and – on ions convey whether they are positive or negative.
Atoms that give up electrons, cations (cations are on the left side of the table, the metals) will have a
positive charge. On the other hand, atoms that add electrons, anions (anions are on the right of the table
and are generally nonmetals) will have a negative charge.
For example, Na will give up 1 electron and Cl will add one electron.
The charge of the ion is also dependent on the charges of the individual atoms in the compound, so for
example:
a fluoride atom has a neutral charge, but an ion has a 1- charge because it has
9 protons+ 10 neutrons+ 10 electrons, which makes it charged negatively.
The general rule when talking about compounds is that the atoms want to reach their octet, or 8 valence
electrons. The protons do not change, this is just a transfer in the valence electrons. This is not always
true; it is just a general guideline.
Ionic bonds are a balance between the force of attraction and repulsion between opposite charged ions.
In crystalline solids (ionic bonds) this is called lattice energy. It is the energy released in the formation of
an ionic compound.
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