How to Get the Total Number of Valences on a Compound

How to Get the Total Number of Valences on a Compound
••• Emilija Randjelovic/iStock/GettyImages

In chemistry, a compound's valence number is the number of bonds formed by the electrons in the last (outer) shell (called valence electrons) of atoms to other atoms' valence electrons. The octet rule (the tendency of an atom to seek stability by filling its outer shell with eight electrons by forming valence electron bonds) can help you determine the valence of a compound once you know the maximum possible valence bonds each element can form.

    Decipher which elements are present in your compound and how many molecules of each element by looking at the abbreviation in the compound name. For example, NaCl has two elements with one molecule of each element, Na (sodium) and Cl (Chlorine), and CaCl2 has two elements with one Ca (Calcium) molecule and two Cl (Chlorine) molecules.

    Determine the number of valence electrons of each element by looking at the the oxidation number column of the chart in the resources section. Some elements have multiple oxidation numbers because there are a number of possible bond combinations between various elements. Use your judgment to determine which number is the correct number for your compound by trying to balance the total charge of each element with the other so that the negative and positive values have a sum of zero. For example, in the compound SO3, Oxygen can have -1 or -2 valence values, and S can have -1, -2, +2, +4 or +6 values but since there are three Oxygen molecules and one Sulfur molecule, each Oxygen molecule must have a value of -2 (total of -6) and each Sulfur molecule a value of +6 to balance to zero (-6 +6 = 0).

    Count the number of bonds necessary to get that zero sum value. You can do this by counting the largest number of valence electrons to be paired (in the previous example, the largest absolutely value was 6).

Related Articles

How to Find an Oxidation Number
How to Calculate the Unsaturation Number
How to Convert Atoms to Grams With a Calculator
How Do I Calculate Molarity?
How to Find the Mass Number of Bromine With 46 Neutrons
How to Count Particles in Chemical Formulas
How to Use the Octet Rule
How to Write a Chemical Compound Formula
How to Find the Number of Unshared Electrons
What Is the Difference Between Molar Mass and Molecular...
How to Write an Isotope
What Are the Particles Formed From Covalent Bonding?
What is an Ionic Compound?
How to Find the Number of Ions in a Compound
How to Tell if a Molecule Is Bent
How to Calculate a Fraction Covalent
Examples of Elements Without a Stable Electron Configuration
Environmental Concerns With Sodium Bicarbonate
How to Create Models of Molecular Compounds
How to Calculate the Normality of NaOH

Dont Go!

We Have More Great Sciencing Articles!