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5.5/5.6 Ions and Ionic Compounds
Learning Goals
(5.5) Define an ion and compare an anion to a cation
(5.6) Draw a Bohr-Rutherford diagram for the following elements: sodium, lithium, fluorine, oxygen,
sulfur, nitrogen, phosphorus, neon, helium
(5.6) State the rules for designing a chemical formula and a chemical name for an ionic compound. Write
names and formulae for ionic compounds
An ion is a charged particle that results when an atom gains or loses
electrons.
 If the atom LOSES electrons, the ion becomes POSITIVE and is
called a CATION.
 If the atom GAINS electrons, the ion becomes NEGATIVE and is
called an ANION.
A Bohr-Rutherford diagram demonstrates how ions form.
Example: A lithium atom (Li: atomic # of 3) has 3 protons therefore 3
electrons in the orbits around the nucleus. A Fluorine atom (F: atomic #
of 9) has 9 protons therefore 9 electrons in the orbits around the
nucleus.
A Lithium ION, however, results when the atom loses the single
electron in the outer most level during a chemical reaction with the
fluorine. The fluorine ION forms when it gains the electron lost by the
lithium. The lithium is now equivalent to Helium and the Fluorine to
Neon in terms of the number of electrons.
 The result is an ionic compound (metal + non-metal) being held
by an ionic bond (cation + anion).
 The chemical FORMULA is LiF because 1 atom of each element
could be combined to create a particle with FILLED ORBITALS.
 The chemical NAME is Lithium fluoride because the cation always
goes first and the anion always ends in “-ide”.
Copy and try these.
1. State the chemical formula for the following combinations of
elements.
 Lithium and Chlorine
 Sodium and Fluorine
 LiCl
 NaF
 Lithium and Oxygen
 Sodium and Sulfur
 Li2O
 Na2S
 Sodium and Nitrogen
 Lithium and Phosphorus
 Na3N
 Li3P
2. State the chemical NAME for the following combinations of
elements.
 Lithium and Chlorine
 Sodium and Fluorine
 Lithium chloride
 Sodium fluoride
 Lithium and Oxygen
 Sodium and Sulfur
 Lithium oxide
 Sodium sulfide
 Sodium and Nitrogen
 Lithium and Phosphorus
 Sodium nitride
 Lithium phosphide
Read section 5.7 and answer the following into your notes. Don’t forget
to include the questions with the answers.
 CYL # 2,3,6 & 7 on page 200