Naming & Writing Ionic Formulas PowerPoint

Naming & Writing Ionic Formulas PowerPoint

1. IONIC COMPOUNDS Naming Ionic Compounds & Writing Formulas What are the rules for naming ionic compounds and writing formulas? 1

2. Writing Ionic Compound Formulas 2

3. Formulas for Ionic Compounds Ionic formulas must be written such that the total positive and negative charges are equal . The charges must be equal to create a neutral compound. The easiest way to do this is to criss-cross the numeric values of the charges to become subscripts on the opposite atom, then simplify (the Swoosh and Reduce Method). 3

4. Formulas for Ionic Compounds Writing Ionic Compound Formulas The “Swoosh and Reduce” Method Write down the chemical symbol for each element (metal first). Write the charge of each element as superscripts above the respective chemical symbol. Swoosh (crisscross) the charges (superscripts) so that they become subscripts of the other element. Write the formula, dropping the “+” and “-” signs and any ones (1). Reduce any subscripts to the simplest form, rewriting the formula if necessary. Check that the formula is neutral. 4

5. Formulas for Ionic Compounds Things to Watch for when Writing Formulas Polyatomic Ions A polyatomic ion is treated as a unit when writing formulas, i.e., never change subscripts of the atoms within the ion and keep the polyatomic ion in brackets. Polyatomic ion charges are given on the back of your periodic table . Roman Numerals Mostly occurs with transition metals (and Pb , Sn, and Sb. The numeral in the parenthesis is the charge on the cation. Ex: iron (II) = Fe 2+ 5

6. Formulas for Ionic Compounds 6 Li and P Mg and Cl Al and N Ca and (CO 3 ) (NH 4 ) and F Step 1 Li P Mg 2+ Cl 1- MgCl 2 Al 3+ N 3- AlN Ca 2+ (CO 3 ) 2- Ca(CO 3 ) (NH 4 ) 1+ F 1- (NH 4 )F Step 2 Li 1+ P 3- Step 3 Li 1+ P 3- Step 4 Li 3 P Step 5 Step 6 Li 3(1+) = 3+ P 1(3-) = 3- Practice

7. Formulas for Ionic Compounds 7 magnesium nitride aluminum nitrate copper (II) oxide Step 1 Mg 2+ N 3- Mg 3 N 2 Al 3+ (NO 3 ) 1- Al(NO 3 ) 3 Cu 2+ O 2- CuO Step 2 Step 3 Step 4 Step 5 Step 6 Practice

8. Naming Ionic Compounds 8

9. Naming Ionic Compounds Naming Cations To name positive (+) ions, write the name of the element and add the word “ion” afterwards. 9 Element Ion Formula Ion Name sodium Na 1+ sodium ion aluminum Al 3+ aluminum ion magnesium Mg 2+ magnesium ion Practice:

10. Naming Ionic Compounds Naming Cations Polyatomic Ions : Refer to the list on the back of the periodic table when naming polyatomic ions. 10 Practice: Ion Formula Ion Name (NH 4 ) 1+ ammonium (HCO 3 ) 1- bicarbonate (CrO 4 ) 2- chromate

11. Naming Ionic Compounds Naming Cations Transition Metals : Determine the charge on the ion (may need to reverse swoosh) and add a roman numeral equal to the ion’s charge in parentheses and end with the word “ion”. While not transition metals, Pb , Sn and Sb should be treated as if they were. 11 Element Ion Formula Ion Name iron (II) Fe 2+ iron (II) ion tin (IV) Sn 4+ tin (IV) ion cobalt (III) Co 3+ Co (III) ion Practice:

12. Naming Ionic Compounds Naming Anions To name negative (-) ions, write the name of the element but replace the ending with “ide” and add the word “ion” afterwards. 12 Element Ion Formula Ion Name bromine Br 1- bromide ion arsenic As 3- arsenide ion oxygen O 2- oxide ion Practice:

13. Naming Ionic Compounds Naming Ionic Compounds Name the metal (cation) first, followed by the nonmetal (anion). Drop the term “ion” from both names . aluminum ion + bromide ion = aluminum bromide 13 Formula Compound Name HCl hydrogen chloride Na(PO 3 ) sodium phosphite Cu(NO 3 ) 2 c opper (II ) nitrate