Ionic Bonding Day 2

1. EQ: What are the guidelines to write and name Ionic formulas? Ionic Bonding Day 2

2. Writing Ionic Formulas • Binary compounds are made up of two elements. • Binary ionic compound are made up of a metal and a nonmetal.

3. Writing ionic formulas Ex: potassium chloride • Write symbols for both ions including charges • Check to see if charges balance K+ Cl- Balanced! Formula is: KCl

4. Writing ionic formulas Ex: calcium bromide • Write symbols for both ions • Check to see if charges balance • If not balanced use subscripts to balance charges Ca2+ Br- Notbalanced! Formula is: CaBr2 1(2+) + 2(1-) = 0

5. Writing Ionic Formulas Ex: calcium sulfide • Write Symbols • Crisscross • Check to see if subscripts can be reduced Ca2+ S2- Formula is: Ca2S2 Reduce!! Formula is: CaS Correct!!

6. Predicting Ionic Charges • Groups 3-12:Many transition elements have more than one charge Iron(II) = Fe2+ Iron(III) = Fe3+ If an element forms more than one ion, a Roman numeral is used to indicate the charge

7. Predicting Ionic Charges • Groups 3-12:Some transition elements have only one oxidation state Zinc = Zn2+ Silver = Ag+ No Roman numeral is used for elements that have only one oxidation state

8. Writing Ionic Formulas Ex: Iron(III) Oxide • Write all symbols • Check to see if charges balance • Use subscripts to balance Fe3+ O2- Not balanced! Formula is: Fe2O3 2(3+) + 3(2-) = 0

9. Writing Ionic Formulas Ex: Iron(III) oxide • Another method for writing balanced formulas is the crisscross method • First write symbols • Charge of one ion is used as subscript for other ion Fe3+ O2- Fe2O3

10. Writing ionic formulas Remember the Steps • Write symbols • Crisscross • Reduce if needed You Practice Sodium iodide Tin(IV) chloride Potassium sulfide Calcium iodide

11. Polyatomic ions • Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge. • For instance the sulfate anion, SO42-,is made up of one sulfur atom and four oxygen atoms and has a 2- charge. • You will need a list of polyatomic ions to determine the name and formula

12. Writing ionic formulas • Ionic compounds that contain a polyatomic ion are called ternary ionic compounds • The names usually end in ate or ite and you need to remember to look up the formula of the polyatomic ion

13. Writing ionic formulas Ex: calcium nitrate • Write symbols • Crisscross to balance • If the polyatomic ion requires a subscript, place parentheses around the ion Ca2+ NO3- ( ) Ca NO3 2

14. Writing ionic formulas Ex: lithium carbonate • Write symbols • Crisscross and write formula using parentheses if needed • Notice that no parentheses are needed if only one polyatomic ion Li+ CO32- Li CO3 2

15. Writing ionic formulas Ex: magnesium hydroxide • Remember that the hydroxide ion also needs parentheses Mg2+ OH- Mg ( OH ) 2

16. Writing Ionic Formulas Remember the Steps • Write symbols • Crisscross • Use parentheses if needed • Reduce subscripts if needed You Practice! ammonium sulfite calcium phosphate magnesium carbonate

17. Naming Ionic Compounds Ex: NaI • Name the first ion • Name the second ion • Remember that negative ions end in ide The name of the compound is: sodium iodide

18. Naming Ionic Compounds Ex: CuO • Name the first ion • Recall that the copper ion can be either Cu+ or Cu2+ • Since O has a 2- charge is must be Cu2+ or Copper(II) • Name the second ion The name of the compound is: copper (II) oxide

19. Naming Ionic Compounds Remember the Steps • Name the first ion • Check to see if it needs a roman numeral • Name the second ion You Practice!! ZnS KCl CuBr2 FeS

20. Naming Ionic Compounds Ex: K2Cr2O7 • If a formula contains three or more elements, it contains a polyatomic ion • You must look up the name • Cr2O72- is the permanganate ion The name of the compound is: potassium permanganate

21. Naming Ionic Compounds Remember the Steps • Name the first and second ions • Remember to check if the metal requires a roman numeral • If it is a ternary compound look up the polyatomic ion You practice!! CaC2O4 Li2S04 Sn3(PO4)2