Ionic CompoundsIonic Compounds

The Loss or Gain of ElectronsThe Loss or Gain of Electrons

Stable AtomsStable Atoms

We know that atoms that are stable have We know that atoms that are stable have either:either:

A filled outer energy level – eight A filled outer energy level – eight electrons (the octet rule).electrons (the octet rule).

Elements will lose or gain electrons to Elements will lose or gain electrons to achieve this state.achieve this state.

Use the periodic table to see how many Use the periodic table to see how many electrons the atom needs to be stable.electrons the atom needs to be stable.Ex. O has 6, but wants 8. It adds 2e’s;Ex. O has 6, but wants 8. It adds 2e’s;It makes the ion OIt makes the ion O-2-2

IonsIons

Ionic compounds start with ionsIonic compounds start with ions When naming an anion we will take the When naming an anion we will take the

beginning of the name and add –ide.beginning of the name and add –ide.

Ex. Cl- is called chloride, not chlorineEx. Cl- is called chloride, not chlorine When naming a cation we just use the When naming a cation we just use the

name of the element plus the word ion.name of the element plus the word ion.Ex. Na+ is called sodium ionEx. Na+ is called sodium ion

Ionic CompoundsIonic Compounds

Ionic compounds are called salts.Ionic compounds are called salts. Consist of a metal and a nonmetal.Consist of a metal and a nonmetal. A cation and an anion. There can be A cation and an anion. There can be

multiples of each.multiples of each. It is the electrostatic attraction It is the electrostatic attraction

(opposites attract) between the (opposites attract) between the positive cation and the negative anion positive cation and the negative anion that holds the compound in the solid that holds the compound in the solid state.state.

Characteristics of Ionic Characteristics of Ionic CompoundsCompounds

Strong bonds.Strong bonds. Solids.Solids. High melting points.High melting points. Exist as crystals with repeating unitsExist as crystals with repeating units Can be soluble (dissolve in water) or Can be soluble (dissolve in water) or

insoluableinsoluable

Naming Ionic Naming Ionic CompoundsCompounds

Always name the cation first.Always name the cation first. Change the suffix of the anion to –ide.Change the suffix of the anion to –ide. If the cation is a transition element the If the cation is a transition element the

name MUST contain a Roman numeral. name MUST contain a Roman numeral. This represents its charge or oxidation This represents its charge or oxidation state.state.

Example: Example: KI – potassium iodideKI – potassium iodideSrClSrCl22 – strontium chloride – strontium chlorideFeFFeF33 – iron(III) fluoride. – iron(III) fluoride.

Polyatomic IonsPolyatomic Ions

Polyatomic ions are ions that consist Polyatomic ions are ions that consist of more than one element. of more than one element.

It is very important to keep in mind It is very important to keep in mind that the charge on the polyatomic ion that the charge on the polyatomic ion belongs to the entire molecule, not to belongs to the entire molecule, not to just one atom within the molecule.just one atom within the molecule.

NONO33-- nitrate polyatomic ion. nitrate polyatomic ion.

SOSO44-2-2 sulfate polyatomic ion. sulfate polyatomic ion.

Polyatomic IonsPolyatomic Ions

You are responsible for memorizing the following You are responsible for memorizing the following polyatomic ions with respect to their formulas, polyatomic ions with respect to their formulas, names, and charges:names, and charges:

(They are found on your ion chart)(They are found on your ion chart)

CHCH33COOCOO-1-1 (C(C22HH33OO22-1-1)) acetateacetate

NHNH44+1+1 ammoniumammonium

COCO33-2-2 carbonatecarbonate

CrOCrO44-2-2 chromatechromate

OHOH-1-1 hydroxidehydroxideNONO33

-1-1 nitratenitrateNONO22

-1-1 nitritenitritePOPO44

-3-3 phosphatephosphateSOSO44

-2-2 sulfatesulfateSOSO33

-2-2 sulfitesulfite

Polyatomic IonsPolyatomic Ions

Ionic compounds containing Ionic compounds containing polyatomic ions are named by:polyatomic ions are named by:

Naming the cation.Naming the cation. Naming the polyatomic ion.Naming the polyatomic ion.

NaNONaNO33 – sodium nitrate – sodium nitrate

Mg(OH)Mg(OH)22 – magnesium hydroxide – magnesium hydroxide

Writing FormulasWriting FormulasTwo methods to writing formulaTwo methods to writing formula

First method- add up charges;First method- add up charges; Write the cation first.Write the cation first. Write the anion last.Write the anion last. First method- The sum of the First method- The sum of the

oxidation numbers or charges must oxidation numbers or charges must equal zero. Ex. Calcium chloride equal zero. Ex. Calcium chloride

CaCa+2+2 2xCl 2xCl-- = -2 CaCl = -2 CaCl22

Second method – criss-crossSecond method – criss-cross

CaCa+2+2 Cl Cl-1-1 = CaCl = CaCl22

Writing and Naming Ionic Writing and Naming Ionic FormulasFormulas

Name the following ionic compounds:Name the following ionic compounds: SrO SrO Al(CH Al(CH33COO)COO)33 CuSO CuSO44

strontium oxidestrontium oxide aluminum acetate aluminum acetate

copper(II) sulfatecopper(II) sulfate

KNOKNO33 CrPOCrPO44 BaIBaI22

potassium nitratepotassium nitratechromium(III) phosphate barium chromium(III) phosphate barium iodideiodide