PS-4.5    Predict the ratio by which the representative elements combine to form binary ionic compounds, and represent that ratio in a chemical formula.
Key Concepts:
Binary ionic compounds
Chemical formula
Balanced charge
It is important to note here that the following is a process that will enable you to determine the binary product of a reaction between metal and nonmetal atoms.
  A binary ionic compound is a chemical combination of two elements. One element is a metal, with a positive+ oxidation number and the other element is a nonmetal with a negative- oxidation number. The product of a reaction between any pair of metal and nonmetal ions can be determined by using the oxidation numbers of the two reactants. It is important to remember that the binary product of a reaction between a metal and a nonmetal must be electrically neutral. Here are several examples of binary ionic reactions.
    Here, the Potassium atom from group 1, gives up a single electron thus making it a positive ion. The Fluorine atom gains a single electron producing a negative ion. Since one positive charge can attract one negative charge, the attraction produces an ionic bond between the two oppositely charged ions. The result of this transfer of valence electrons between the atoms is an ionically bonded formula unit consisting of one atom of Potassium and one atom of Fluorine...that's a 1/1 ratio of K to F atoms.
Here is another example. Note that in this example the product is not a 1/1 ratio.
  In this example, a single Sodium atom can give up a single electron leaving the Sodium atom with a 1+ charge. However, single Oxygen atom can take in TWO electrons. There must be another Sodium atom somewhere to give up another electron. So the resulting product is Na2O. It takes two Sodium atoms, each giving up a single electron, to give a single Oxygen atom two electrons. The result of this transfer of valence electrons between the atoms is an ionically bonded formula unit consisting of two atoms of Sodium and one atom of Oxygen...that's a 2/1 ratio of Na to O atoms.
**Here is another way to determine the ionic binary product from the last example.
In this example, the charge of the two oxidation numbers have been dropped and the two integers ( 1 and 2) cross over to become the subscript on opposite ions. Using this method gives the correct ratio of metal and nonmetal ions. Here ar several examples you can try to solve.
            Click here to see the complete reaction
        Click here to see the complete reaction
       Click here to see the complete reaction
     Click here to see the complete reaction
      Click here to see the complete reaction