Chemical Names of Ionic Compounds Lesson 7

What are Ionic Compounds? Ionic compounds are made up of positive and negative ions. All of the positive and negative ions for a pattern Negative and positive ions attract. Negative and negative and positive and positive repel. Ionic compounds form solid crystals. Ionic compounds are like a solid stack of bricks.

Where does our salt come from?

Naming Ionic Compounds Formula for naming ionic compounds positive ion + negative ion + -ide. If a compounds contains 2 elements the first is ALWAYS a metal If a compounds contains 2 elements the second is ALWAYS a non-metal For example: magnesium (metal) and oxygen (non-metal). STEP 1: The positive ion is the first part of the name STEP 2: The negative ion forms part of the ending of the name STEP 3: Add -ide to the end of the name magnesium oxygen -ide Magnesium oxide

Try these Calcium and Bromine Calcium bromide Lithium and Nitrogen P 186-187 text Calcium and Bromine Lithium and Nitrogen Zinc and Sulfur Calcium bromide Lithium nitride Zinc sulfide

Writing formulas for Ionic Compounds Ionic formulas are based on the ions of the atoms involved Example: What is the name of Ca3N2? Ca is the positive ion and is calcium. N is the negative ion and is nitrogen. Drop the ending of the negative ion, nitrogen and add -ide. Calcium nitride

Writing formulas for Ionic Compounds continued Rules for writing formulas of ionic compounds In an ionic compound, the positive charges balance out the negative charges. The ratio of positive to negative charges gives the proper formula. The ratio is always written in reduced form.

Example: Hydrogen chloride Identify each ion and its charge Determine the total charges needed to balance positive and negative Note the ratio of positive ions to negative ions Use subscripts to write the formula, 1’s are not shown in subscript H+ and Cl- ions Total charge to balance +1 = -1 ratio 1 : 1 formula HCl

Example: Potassium and Sulfur K+ and S2- ions Total charge to balance +1+1 = -2 ratio 2 : 1 formula K2S

Example: Aluminum and Sulfur Al3+ and S2- ions Total charge to balance +3+3 = -2-2-2 ratio 2 : 3 formula Al2S3

Formulas are always written in their most reduced form Ca2+ and O2- ions Total charge to balance +2 = -2 ratio 1 : 1 formula Ca2O2 Simplify and write in most reduced form CaO

Homework Key Points from Today Workbook, p62 #1-3 Name of a compound=words (element names spelled out) Formula of a compound=symbols (element symbols and subscripts) Homework To help you practice naming ionic compounds and writing ionic formulas Workbook, p62 #1-3 Text book, p187 #1 a,c,e,g,h,i