Chemistry 3.2 Naming Ionic Compounds Science 9

By the end of this lesson you should be able to… Objectives By the end of this lesson you should be able to… Write the formulas for ionic compounds Including compounds with multivalent and polyatomic ions Write the names of ionic compounds

Ionic Compounds All ionic compounds are composed of positive and negative ions The positive ions are donating (or giving) their electrons to the negative ion.

Chemical Names International Union of Pure and Applied Chemistry (IUPAC) Represents chemists around the world Came up with rules for naming

Naming Rules For Ionic Compounds The first part of the name always comes from the positive ion The metal The second part of the name comes from the negative ion The non-metal Non-metals (negative ions) name always changed to an “ide” ending

Non-Metal Endings Non-metals (negative ions) name always changed to an “ide” ending Symbol Name F- fluoride Cl- chloride Br- bromide I- iodide O2- oxide S2- selenide N3- nitride P3- phosphide

Naming Example NaCl The first part of the name always comes from the positive ion The second part of the name comes from the negative ion Non-metals (negative ions) name always changed to an “ide” ending Sodium Chlorine Chloride

Naming Example NaCl The first part of the name always comes from the positive ion The second part of the name comes from the negative ion Non-metals (negative ions) name always changed to an “ide” ending Sodium Chlorine Chloride

Practice AlI3 Na2O Mg3P2 CaSe AgI Aluminum iodide Sodium oxide Magnesium phosphide Calcium selenide Silver iodide

Writing Formulas Rules Hand out cut outs Rules In ionic compounds the positive charges balance out the negative charges Get the symbols and their charges Criss Cross the charges and delete the signs You don’t need to write in 1’s

Writing Formulas Example Berylium and Nitrogen Rules In ionic compounds the positive charges balance out the negative charges Get the symbols and their charges Criss Cross the charges and delete the signs Be N Berylium: Be2+ Nitrogen: N3- 3- 2+ Be3N2

Important The final formula must be in the smallest whole number ration Ex. Sn4+ O2- 4+ 2- Sn O Sn2O4 WAIT! Your not finished yet SnO2

Practice Write the formulas of.. a) Lithium with Chlorine b) Calcium with Fluorine c) Sodium with Sulphur d) Lithium fluoride e) Silver sulphide LiCl CaF2 Na2S LiF Ag2S

MultiValent Metals Look at Iron (Fe) on your periodic table What do you notice about it? How would we write the formula for Iron and Clorine. 2 different charges +2 and +3 ! Would it be FeCl3 OR FeCl2

Solution We need to specify if we are talking about Fe3+ or Fe2+ We use Roman Numerals to name these multivalent atoms The Roman Numeral tells us the charge on the metal. Charge Roman Numeral 1+ I 2+ II 3+ III 4+ IV 5+ V 6+ VI 7+ VII

Naming with Multi-Valent Ions The first part of the name always comes from the positive ion The metal Put the roman numeral for the charge in brackets after you name the metal. The second part of the name comes from the negative ion The non-metal Non-metals (negative ions) name always changed to an “ide” ending

Naming with Multi-Valent Ions ex. FeCl3 The first part of the name always comes from the positive ion iron Put the roman numeral for the charge in brackets after you name the metal. Charge is 3+ Roman numeral III The second part of the name comes from the negative ion Chlorine Non-metals (negative ions) name always changed to an “ide” ending Chloride Iron (III)

Naming with Multi-Valent Ions ex. FeCl3 The first part of the name always comes from the positive ion iron Put the roman numeral for the charge in brackets after you name the metal. Charge is 3+ Roman numeral III The second part of the name comes from the negative ion Chlorine Non-metals (negative ions) name always changed to an “ide” ending Iron (III) Chloride

Formulas with Multivalent ions Rules are very similar In ionic compounds the positive charges balance out the negative charges Get the symbols and their charges For the multivalent ion use the charge given in the brackets Criss Cross the charges and delete the signs You don’t need to write in 1’s

Fe Cl Fe Cl Ex. Iron (III) Chloride Get the symbols and their charges For the multivalent ion use the charge given in the brackets Criss Cross the charges and delete the signs You don’t need to write in 1’s 3+ _ Fe Cl 3+ 1- Fe Cl Formula is FeCl3

Polyatomic Ions Found on your periodic table Always paired up with ions that have the opposite charge They contain covalent bonds but have an overall charge You do not need to memorize these since they are on your periodic table!

Naming Polyatomic ions Follow the same naming rules as before Make sure you name the positive ion THEN the negative ion But do not change the endings of the polyatomic ions Keep the name as it is written on the periodic table

Formulas for polyatomic ions BRACKETS, BRACKETS, BRACKETS When writing a formula that includes a polyatomic ion, if there is a subscript (little number next to the polyatomic ion) you must use brackets Examples on the board

Your Turn Finish naming and formula practice page Work on mixed up naming worksheet