Chemistry - Tips on how to Produce Covalent along with Ionic Chemical Formulas.

Writing chemical formulas is a necessary skill if you are likely to be successful in chemistry. Balancing equations, predicting reactions and calculating stoichiometric problems all rely on your power to properly write a chemical formula. If you make a mistake in the formula it'll affect the balancing and the mole ratios used to do stoichiometric calculations. So take the time to discover ways to properly write chemical formulas, you'll be glad you did.

What You Need to Know...

1. Just how to utilize the Periodic Table
2. How to make use of subscripts
3. How to determine ionic charges
4. Polyatomic ions
5. Metals with multiple charges
6. Greek and Latin numeric prefixes

The General Rule

Most compounds consist of two parts (binary) and are classified as ionic or covalent. The typical rule for naming and writing compounds is to put the more metallic element first followed by the less metallic element. Remember to make use of subscripts showing the amount of atoms or ions contained in the formula.

Writing Ionic Formulas

When writing the chemical formula for ionic compounds place the cation first, then your anion and check to see that the charges balance to zero. RM257 If the charges aren't balanced, you must increase the amount of cations and anions before the algebraic sum of the charges is zero.

• If the charges are (2+) and (3-) the sum is (1-) and is not balanced. But the cheapest common multiple of 2 and 3 is 6. So using subscripts increase the amount of cations by 3 and the amount of anions by 2.


• Thus (2+) times 3 is (6+) and (3-) times 2 is (6-) and (6+) + (6-) is zero. Balanced.

If the cation has multiple charges, the appropriate charge is indicated by a Roman numeral placed after the cation's name. Remember to deal with polyatomic ions as complete unit, do not separate them.

EXAMPLE #1: calcium chloride is CaCl2 (calcium 2+) (chlorine 1-) increase the chlorine to two.

EXAMPLE #2: lithium nitrate is LiNO3 (lithium 1+) (nitrate 1-) balanced.

EXAMPLE #3: iron (II) sulfate is FeSO4

Writing Molecular Formulas (covalent)

When writing the chemical formula for covalent compounds place the less electronegative element first followed by the more electronegative element and use subscripts to point the amount of atoms present. Understand that prefixes are used only with covalent compounds.

EXAMPLE #1: co2 is CO2 (1 C) (2 O)

EXAMPLE #2: phosphorous pentachloride is PCl5 (1 P) (5 Cl)

Don't Forget to Practice

Really, that's all there's to writing chemical formulas. So you need to apply, practice and practice some more. Although chemical formulas aren't all that hard, you will need to apply if you are likely to be worthwhile at it.