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Naming Ionic Compounds. Warm Up – Putting it together. What is a compound? Draw a Bohr-Rutherford diagram of a Hydrogen and Oxygen atom How do you think the compound H 2 O is formed? . Learning Goals. By the end of class, I will be able to : Understand how ionic compounds are formed
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Warm Up – Putting it together What is a compound? Draw a Bohr-Rutherford diagram of a Hydrogen and Oxygen atom How do you think the compound H2O is formed?
Learning Goals • By the end of class, I will be able to: • Understand how ionic compounds are formed • Write the chemical formula for ionic compounds • Name ionic compounds
Ionic Compounds • An ionic compound is formed from one or more positively charged ions and one or more negatively charged ions • Eg: Sodium + Chlorine = Sodium Chloride (NaCl)- Table Salt! • Ions form when atoms of different elements combine in a process involving the transferof electrons from one atom to another
Notice BOTH ions have EIGHT valence electrons! (outermost shell electrons)
Remember… • ~ METALS tend to LOSE electrons, becoming POSITIVE • ~ NON-METALS tend to GAINelectrons, becoming NEGATIVE
NamingUnivalent Ionic Compounds • Name the metal ion first. • - The name of the compound ion is the same as the element name. • Name the non-metal ion second. • - When a non-metal becomes a negative ion, the ending of is name changes to “ide”. • Name the ionic compound by combining the ion names.
Naming Univalent Ionic Compounds Calcium oxide Cesium nitride Magnesium chloride Lithium bromide Potassium phosphide Sodium sulfide
All ion charges in an ionic compound MUST add up to ZERO – the compound itself has no net charge ~ The positive and negative charges of an ionic compound must be equal ~
Writing Formulas for Ionic Compounds • ~ The chemical formula may include one or more subscripts • ~ The subscripts tell you the ratio of each ion that is in that compound (NOTE: When there is no subscript, there is only one of that ion) • Sodium chloride ~ NaCl(1 sodium ion :1 chlorine ion) • Magnesium chloride~ MgCl2(1 Mg ion: 2 Cl ions)
How do you determine if the chemical formula includes a subscript? REMEMBER! The positive and negative charges in an ionic compound MUST equal.
Steps for Writing Formulas for Ionic Compounds Magnesium: Mg2+ Chloride: Cl1- Mg2+ Cl1- Cl1- 1 to 2 MgCl2
Practice • Write the chemical formula for these ionic compounds • (a) Lithium iodide • (b) Calcium bromide • (c) Aluminum chloride • (d) Magnesium fluoride
Challenge #1 – Complete with a Partner • Are the following ionic compounds possible? Explain why or why not. • (a) Ca2P3 • (b) LiI • (c) NaBr
Challenge #2 – Complete with a Partner • What do you do if an ion has two or more possible charges? • Give examples to support your answer.
Practice & Homework 1. Ionic Compounds – Names and Formulas Worksheet 2. Textbook questions in Weekly Outline
Crisscross Rule for Writing Formulas Step 1: Write the symbols of each element (remember to write the symbol for the metal first) Step 2: Write the ion charge above each corresponding symbol. Remember that the ion charge is based on the number of electrons gained (negative) OR lost (positive) to become an ion. Step 3: Crisscross the ion charges, erase the signs of each ion charge, and write them as subscripts
Examples of Writing Formulas • Write the correct formula for a compound of aluminum and sulphur • (a) 3+ 2- Al S = Al2S3
Examples of Writing Formulas • Write the correct formula for a compound of barium and oxygen • (b) 2+ 2- Ba O = Ba2O2 Note: If you need the same number of each ion, you can reduce the formula to one of each ion, as shown here. = BaO