Lesson 20 Getting Connected Ionic Compounds Chem Catalyst

Lesson 20: Getting Connected Ionic Compounds

Chem. Catalyst Metal elements combine with the nonmetal element chlorine, Cl, to form compounds. The formulas are given in the tables. Element Compound Na Na. Cl Mg Mg. Cl 2 Ne none K KCl Ca Ca. Cl 2 Ar none 1. Compare three tables. What do you notice? 2. Predict the formula of a compound formed between lithium, Li, and chlorine, Cl. Which table would you put it in?

Key Question How can valence electrons be used to predict chemical formulas?

Objectives: • • predict the chemical formulas of compounds that will form between metal and nonmetal atoms explain how an ionic compound forms and determine whether it follows the rule of zero charge

Prepare for the Activity Work in pairs. Ionic compound: An ionic compound is a compound composed of positive and negative ions, formed when metal and nonmetal atoms combine.

Lesson 20 Notes a. )Metal and nonmetal elements combine to form ionic compounds. EX: Mg 2+ + Cl– produces Mg. Cl 2 with zero charge.

Notes (cont. ) b. )The rule of zero can be used to determine the chemical formulas Rule of zero charge: In an ionic compound, the positive and negative charges add up to 0. c. ) Use a SUBSCRIPT when you need more than one of any element

Notes (cont. ) d. ) When naming the compound: • Cation = unchanged • Anion = ending changed to –ide Ex: Mg. Cl 2 = magnesium chloride Ca. O = calcium oxide

Check-in 20 What would be the chemical formula if Strontium (Sr) formed an ionic compound with Bromine (Br)?