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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.
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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.
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 Magnesiumoxide
Try these P 186-187 text • Calcium and Bromine • Lithium and Nitrogen • Zinc and Sulfur Calcium bromide Lithiumnitride Zincsulfide
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 Name of a compound=words (element names spelled out) Formula of a compound=symbols (element symbols and subscripts) • Workbook, p62 #1-3 • Text book, p187 #1 a,c,e,g,h,i To help you practice naming ionic compounds and writing ionic formulas