Naming Ionic CompoundsNaming Ionic Compounds

Monatomic IonsMonatomic IonsMade from a single atom gaining or

losing an electron (based on valence electrons) Element Oxidation #

Li +1Be +2O -2F -1

Writing ions- write symbol, write charge as a superscript

Ex. Al+3

Writing Ionic CompoundsWriting Ionic CompoundsMade of two parts – cation &

anionName the cation first (typically a

metal) just as it appears on periodic table

Na+ SodiumCa+2 Calcium

Writing Ionic Compounds Writing Ionic Compounds with Transition Metalswith Transition MetalsMost transition metals have more

than one oxidation numberIf the transition metal has more

than one oxidation number, you must represent it with a Roman Numeral in its name

Transition Metals to knowTransition Metals to knowScandium column – always +3,

no Roman Numeral neededF-block – always +3, no Roman

Numeral neededAg – always +1, no Roman

Numeral neededCd & Zn – always +2, no Roman

Numeral needed

Transition Metals to know Transition Metals to know (cont.)(cont.)Sn & Pb – either +2 or +4Sn & Pb and all other transition

metal’s oxidation # will be determined by “uncrossing the criss-cross”

(I’ll explain in a minute)Examples:

Fe+2 Iron II Fe+3 Iron IIIAl+3 Aluminum Cu+2 Copper IICu+ Copper I Zn+2 Zinc

Writing Ionic Compounds Writing Ionic Compounds (cont.)(cont.)Write the anion next (typically a

nonmetal)Change the ending to –ide

Cl- , chlorine chlorideO-2 , oxygen oxide

**If the anion is a polyatomic ion, the name stays the same**

Writing Ionic Compounds Writing Ionic Compounds PracticePracticeNaClFeSAlCl3Na2O

Al2O3

CuO

Sodium ChlorideIron II SulfideAluminum

ChlorideSodium OxideAluminum OxideCopper II Oxide

How to determine the How to determine the Oxidation Number of Oxidation Number of Transition MetalsTransition MetalsIdentify metal as a Transition with

multiple oxidation numbersUncross the “criss-cross”If nothing to uncross, identify the

charge of the anion (they will always only have one oxidation number), charges have been simplified

Transition metal charge is the same as anion charge (just +)

How to determine the How to determine the Oxidation Number of Oxidation Number of Transition Metals (cont.)Transition Metals (cont.)Ex. #1

Fe2O3

+3 -2

Fe2O3

Iron III Oxide

How to determine the How to determine the Oxidation Number of Oxidation Number of Transition Metals (cont.)Transition Metals (cont.)Ex.#2

FeS**No subscripts to show charge, so

ID anion chargeS = -2, therefore Fe must be +2 Name = Iron II SulfideEx.#3

CuOName = Copper II Oxide

Writing an Ionic FormulaWriting an Ionic FormulaIdentify the charge on each part

of the compound (cation and anion)

Remember…the sum of the oxidation numbers MUST EQUAL ZERO

Add subscripts to balance charges (can be done with criss-cross method)

Writing an Ionic Formula Writing an Ionic Formula (cont.)(cont.)Ex. #1 = Calcium Chloride

Ions Ca = +2 Chlorine = -

1

+2 -1 Ca ClFormula = CaCl2

(Remember…never write 1’s)

Writing an Ionic Formula Writing an Ionic Formula (cont.)(cont.)Ex.#2 = Magnesium Oxide

Ions Mg = +2 O = -2

Use “criss-cross” Mg2O2

**Simplify when possible MgO

Extra RuleExtra RuleCan’t change a Polyatomic Ions

subscripts (if you need multiple polyatomics, you must put the ion symbol in brackets)Ex. PO4 = has a -3 charge

Ca = has a +2 chargeFormula = Ca3(PO4)2

Changes to Polyatomic Changes to Polyatomic IonsIonsWe must know the “root”

polyatomic ion (the ones on our list)

Oxygens can either be added or subtracted from the formula we know

When that happens, the polyatomic ion name changes

Changes to Polyatomic Ions Changes to Polyatomic Ions (cont.)(cont.)1 more oxygen per- -ateRoot -ate1less oxygen -ite2 less oxygens hypo- -ite

**the charge remains the same**Ex. SO5 = Persulfate SO4 =

SulfateSO3 = Sulfite SO2 = hyposulfite