Lesson 12: Ionic Compounds & Formulas and Naming for Multivalent Metals

What does multivalent mean? Compounds with multivalent metals are written with Roman numerals in the chemical name (ie. manganese (IV) oxide) Multivalent – metals that form ions in more than one way The Roman Numeral tells you two things: The metal can form ions with different charges The charge on the metal ion. The most common ion is listed first Look at your periodic table. (What is the most common ion for Cu? Au?)

What is the arrow pointing at?

What are multivalent ions? It’s pointing at Copper which is a multivalent metal. Copper has 2 ion forms It forms a 1+ or 2+ ion Copper I Chloride Copper II Chloride

Roman Numerals Use roman numerals from I – VII which corresponds to 1+ - 7+ ion charges For example: Nickel can have two ion forms, Ni2+ and Ni3+ These are named nickel (II) and Nickel (III) Metal Ion charge Roman Numeral 1+ I 2+ II 3+ III 4+ IV 5+ V 6+ VI 7+ VII

Steps for writing formulas for multivalent compounds Step 1: Identify each ion and its charge Example: Iron (III) bromide Fe3+ Br -

Steps for writing formulas for multivalent compounds Step 2: Use subscripts to write the formula (use the same swap and drop method) Example: Fe3+ Br - FeBr3

Steps for writing formulas for multivalent compounds Step 3: Double Check - does the total number of (+) and (-) ions in the compound balance to zero? FeBr3 1Fe3+ : +3 3Br-: -1, -1, -1 TOTALS

Try the formula for titanium (IV) nitride Ti4+ and N3-

Steps for writing formulas for multivalent compounds Step 1: Identify each ion and its charge Example: Titanium (IV) nitride Ti4+ N3-

Steps for writing formulas for multivalent compounds Step 2: Use subscripts to write the formula (use the same swap and drop method) Example: Ti4+ N3- Ti3N4

Steps for writing formulas for multivalent compounds Step 3: Double Check - does the total number of (+) and (-) ions in the compound balance to zero? Ti3N4 3Ti4+ : +4 +4 +4 4N3-: -3, -3, -3 -3 TOTALS

Writing formulas for compounds that contain a multivalent metal Key Points to remember: The metal is always first The metal is always the positive ion The metal could be a multivalent metal Go to the periodic table and check

Steps for Writing formulas for compounds that contain a multivalent metal Step 1: Identify a metal and its charge from the periodic table. Example: Cu2S Metal is Cu. Cu can be Cu+2 or Cu+1

Steps for Writing formulas for compounds that contain a multivalent metal Step 2: Determine the ratio of ions in the formula Example: Cu2S This formula means there are 2 copper ions for every 1 sulphide ion: 2 Cu : 1 S

Steps for Writing formulas for compounds that contain a multivalent metal Step 3: Note the charge of the (-) ion from the periodic table Example: Cu2S Sulphur has a charge on 2-

Steps for Writing formulas for compounds that contain a multivalent metal Step 4: Choose the charge from the (+) ion that balances out the formula Example: Cu2S 2 Cu: ____ ____ 1S: 2- 0 What charge for Cu should we use +1 or +2 ?

Steps for Writing formulas for compounds that contain a multivalent metal Step 4: Choose the charge from the (+) ion that balances out the formula Example: Cu2S 2 Cu: 1+ 1+ 1S: 2- That’s right - we should use the 1+ charge as that balances the charges to zero

Steps for Writing formulas for compounds that contain a multivalent metal Step 5: Write the name of the compound Example: Cu2S 2 Cu: 1+ 1+ 1S: 2- 0 Since we used the 1+ charge the name of the compound is: copper (I) sulphide

Your turn to try some….. complete the problems in your note package as well as the one’s in the booklet given out.