Naming & Writing Formulas Ch 5 - Ionic Compounds Naming & Writing Formulas

Remember usually In an ionic compound Naming is EASY PEASY! 1st element is a + metal ion 2nd element is a – nonmetal ion Naming is EASY PEASY! 1st element’s name doesn’t change 2nd element’s name ends in –ide Transition metals need to show Roman Numeral polyatomic ions keep their own names

Naming Nonmetal Anions

Transition Metals – Use Systemic Name

What are Polyatomic Ions Groups of elements that act as a group The charge is on the entire group NEVER change formula of polyatomic ions Put them in parenthesis if need be. is written as SO4 -2 Ex. compounds: BaSO4 Barium Sulfate Fe2(SO4)3 Iron III Sulfate

Common Polyatomic Ions

Examples 1. Regular 2. Transitional Metals 3. Polyatomic Ions NaF – Sodium Fluoride CaO – Calcium Oxide 2. Transitional Metals FeCl3 – Iron III Chloride (Fe+3 because 3 Cl- in formula) CuI – Copper I Iodide (Cu+1 because one I- in formula) 3. Polyatomic Ions BaSO4 – Barium Sulfate NH4OH – Ammonium Hydroxide

Mixed Practice BaI2 Ca(OH)2 FeCO3 Na2Cr2O7 Cu(ClO4)2 Barium iodide Calcium hydroxide Iron (II) carbonate Sodium dichromate Cupric perchlorate

Writing Ionic Formulas Compounds are neutral: +ions & – ions have to balance Steps Write the + ion first Write the – ion second Compare oxidation numbers (charges) If the same, you are done If different, criss-cross as subscripts Never change polyatomic ions (use parenthesis if needed)

Formula of Ionic Compounds Al2O3 Al3+ O2- CaBr2 Ca2+ Br- Na2CO3 Na+ CO32-

Try it out… Write the formula for a combination of these ions:

Try it Out Write the formula of these ionic compounds: