Ionic Formulas and Names Topic #14

Ionic Compounds Chemical Formula- tells you how many cations and anions exist in a compound. Binary Compounds- compounds consisting of 2 elements Ternary Compounds- compounds consisting of three different elements.

Writing Ionic Formulas: Rules Rule 1 The positive ion is placed first in the formula, the negative ion is second. For example, KF, CaO

Rule 2 Positive and negative ions are combined so that the total number of positive charges is balanced by the total number of negative charges. For example, CaS, CaCl2, AlCl3 and Al2O3

Rule 3 When there are two or more of a particular ion in a compound, then in the chemical formula the number is written as a subscript after the chemical symbol. For example, Al2O3 IMPORTANT when writing formulas, never write charges, although the ions still have a charge because that’s what keeps them bonded.

Charges of Representative Elements Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Ionic Naming Compound Names generally consist of two words. For ionic compounds, name the cation first then the anion. Remember the anion should end in –ide. Note: Notice how it does not matter the number of ions, the name simply states the cation and the anion Compound Formula Name CaCl2 Calcium Chloride NaBr Sodium Bromide Al2S3 Aluminum Sulfide