Naming and Writing Ionic Compounds

Ionic Compounds Occur between a metal and non-metal Occur when electrons are transferred between atoms forming ions Metals make cations = positive ions Nonmetals make anions = negative ions Also use these rules when a polyatomic ion is present

Ionic Bonding Using Lewis Dots In ionic bonding, electrons are transferred K + F Mg + I Al + Br Be + S Na + O Na + Cl Ca + Cl

Do you see a pattern K +1 + F -1 Mg +2 + I -1 Al +3 + Br -1 KF MgI 2 AlBr 3

Use the pattern to write these formulas: Ca + P Na + O Li + S

Writing Ionic Compounds

7 Guide to Writing Formulas from the Name Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

1. Identify the Ions Look at the group they are in on the periodic table Determine the type of ion created and assign an oxidation number (charge) BeBr Group 2 Group 7 2 electrons7 electrons Be +2 Br -

2. Criss-Cross Charges Criss-Cross Charges Drop Signs Do not write any “1’s” Be +2 Br - Be 1 Br 2 BeBr 2

3. Reduce/Simplify Reduce any subscripts to the simplest form or simplest ratio. LiBr 2 is already simplified But copper(II) oxide needs to be reduced since 2:2 atoms is the same as 1:1. Cu +2 O -2  Cu 2 O 2  CuO

11 Learning Check Write the formulas of the following ions: Br − S 2− N 3− Na + Al 3+

Naming Ionic Compounds

Naming Ionic Compounds with Two Elements

1. Identify the cation and anion Reverse Criss-Cross Al 2 S 3 Al +3 S -2

2. Name the Cation Al +3 S -2 The cation is the positive ion Use its element name Al +3 = Aluminum

3. Name the Anion Al +3 S -2 The anion is the negative ion Use the element name, but change the last part to -ide S -2 = Sulfur  Sulfide

4. Put it together Cation name is first Anion is second Al 2 S 3 Al +3 S -2 Aluminum Sulfide

18 Write the names of the following compounds. 1) CaO___________ 2) KBr___________ 3) Al 2 O 3 ___________ 4) MgCl 2 ___________ Learning Check

19 Write the names of the following compounds: 1)CaOcalcium oxide 2)KBrpotassium bromide 3)Al 2 O 3 aluminum oxide 4)MgCl 2 magnesium chloride Solution

Other Things to Watch Out for….

Roman Numerals Needed/appears only with transition metal The numeral in the parenthesis is the charge Write in parenthesis after element name – Cu +2 O -2 = copper(II) oxide – copper(II) oxide = Cu +2 O -2

Polyatomic Ions When a group of atoms acts like one ion Use the same rules as other ions when writing: Place entire polyatomic ion in parenthesis when criss-crossing – Use cheat sheet for their charges instead of a periodic table Use name on cheat sheet when naming

Example (writing formula): Zinc(II) Hydroxide – Zn = Transition Metal = Zn +2 – OH = Polyatomic ion = (OH) - Zn +2 (OH) - Zn(OH) 2

Example (naming compound): Pb = Lead (a transition metal) NO 3 is a polyatomic ion Pb(NO 3 ) 2 Pb +2 NO 3 -1 Lead (II) Nitrate

Learning Check Select the correct name for each. What is the correct formula for each of the following? 1. Fe 2 S 3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide 2. CuO 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide Copper(I) nitride a)CuN b) CuN 3 c) Cu 3 N 4. Lead(IV) oxide a) PbO 2 b) PbO c) Pb 2 O 4

Solution Select the correct name for each. What is the correct formula for each of the following? 1.Fe 2 S 3 iron (III) sulfide Fe 3+ S 2- 2.CuO copper (II) oxide Cu 2+ O Copper(I) nitride Cu 3 N Need 3Cu + and N Lead(IV) oxide PbO 2 Need Pb 4+ and 2O 2-

Learning Check Name these: Write Formulas: 1. Na 2 SO 4 2. Mg(NO 2 ) Aluminum Hydroxide 4. Zinc (II) Phosphate

Solution Name these: Write Formulas: 1.Na 2 SO 4 Sodium Sulfate 2.Mg(NO 2 ) 2 Magnesium Nitrite Aluminum Hydroxide Al +3 OH -1 Al (OH) 3 4. Zinc (II) Phosphate Zn +2 (PO 4 ) -3 Zn 3 (PO 4 ) 2