Naming & Writing Ionic Formulas

Learning Goal To recall our knowledge about ionic bonds To learn how to name them!

Ionic Bonding When an atom has only a few electrons in this outermost shell, (like Sodium and Magnesium) it is part of the METALS family in the periodic table   Metals like to GIVE AWAY their electrons in order to be Happy Remember: It is easier to give away 1 or 2 electrons than it is to try and get 6 or 7 more! An IONIC BOND happens when a METAL gives away its electron(s) to a NON- METAL

Ionic Bonding: Example

Naming Ionic Compounds with Two Elements To name a compound that contains two elements, identify the cation and anion. Name the cation first followed by the name of the anion.

Charges of Representative Elements

Names of Some Common Ions

Learning Check - CRisscross Write the formulas and names for compounds of the following ions: Br− S2− N3− Na+ Al3+

Solution - Crisscross Na+ Al3+ NaBr sodium bromide Na2S sodium sulfide Br− S2− N3− Na+ Al3+ NaBr sodium bromide Na2S sodium sulfide Na3N sodium nitride AlBr3 aluminum bromide Al2S3 aluminum sulfide AlN aluminum nitride

Recall: IONIC COMPOUNDS A formula unit is the lowest whole number ratio of ions in an ionic compound i.e. Mg2O2 -> MgO

NAMING COMPOUNDS Your ability to name compounds and write formula’s hinges on your ability to recognize whether a compound is made up of a metal + non-metal or just 2 non-metals

BINARY IONIC COMPOUNDS Binary means 2 elements Ionic means a metal and a non-metal (or cation and anion) Writing Formulas • charges must balance so compound charge is neutral.

BINARY IONIC COMPOUNDS Writing Formulas from Names • 1st word = CATION • 2nd word = ANION name with ide ending.

BINARY IONIC COMPOUNDS NaBr MgF2 Sodium Bromide Magnesium Fluoride

BINARY IONIC COMPOUNDS Potassium Chloride Aluminum Oxide • notice ending of name is ide! K+Cl- -> KCl Al3+O2- -> Al2O3

Transition Metals form Positive Ions Most transition metals and Group 4(14) metals form 2 or more positive ions. Zn2+, Ag+, and Cd2+ form only one ion.

Metals that form more than One Cation The name of metals with two or more positive ions (cations) use a Roman numeral to identify ionic charge. Lead Pb2+ lead(II) Pb4+ lead(IV)

Naming Ionic Compounds with Variable Charge Metals

Naming Variable Charge Metals Transition metals with two different ions use a Roman numeral after the name of the metal to indicate ionic charge.

Naming FeCl2 To name FeCl2 1. Determine the charge of the cation using the charge of the anion (Cl-). Fe ion + 2 Cl- = Fe ion + 2- = 0 Fe ion = 2+ 2. Name the cation by the element name and add a Roman numeral in parenthesis to show its charge. Fe2+ = iron(II) 3. Write the anion with an ide ending. FeCl2 = iron (II) chloride

Naming Cr2O3 To name Cr2O3 1. Determine the charge of cation from the anion (O2-). 2 Cr ions + 3 O2- = 0 2 Cr ions + 3(2-) = 0 2 Cr ions - 6 = 0 2 Cr ions = +6 Cr ion = 3+ = Cr3+ 2. Name the cation by the element name and add a Roman numeral in parenthesis to show its charge. Cr3+ = chromium (III) 3. Write the anion with an ide ending. chromium(III) oxide = Cr2O3

Learning Check Select the correct name for each. A. Fe2S3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide B. CuO 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide

Solution Select the correct name for each. A. Fe2S3 3) iron (III) sulfide Fe3+ S2- B. CuO 3) copper (II) oxide Cu2+ O2-