Naming Ionic and Molecular Compounds. Naming Compounds Helps get rid of the confusion that can result from inaccurately naming compounds Helps get rid.

Naming Ionic and Molecular Naming Ionic and Molecular CompoundsCompounds

Naming CompoundsNaming Compounds

Helps get rid of the confusion that can Helps get rid of the confusion that can result from inaccurately naming result from inaccurately naming compoundscompounds• Example: black board chalk and the chalk in Example: black board chalk and the chalk in

TUMSTUMS Naming compounds also shows the Naming compounds also shows the

importance of using names that provide importance of using names that provide information about the chemical information about the chemical composition of a substancecomposition of a substance

The International Union of Pure and The International Union of Pure and Applied Chemistry (IUPAC) is the body Applied Chemistry (IUPAC) is the body responsible for naming compounds.responsible for naming compounds.

Ionic CompoundsIonic Compounds

Form when electrons transfer from one Form when electrons transfer from one atom to another.atom to another.• Example: Sodium Chloride (NaCl) Example: Sodium Chloride (NaCl) ““table table

saltsalt”” Positively charged sodium ions are attracted Positively charged sodium ions are attracted

to negatively charged chloride ions.to negatively charged chloride ions. The two kinds of ions group together in an The two kinds of ions group together in an

organized array called a crystal lattice.organized array called a crystal lattice. The lattice is made up of one such sodium ion The lattice is made up of one such sodium ion

for every one chloride ionfor every one chloride ion Such a neutral unit is called a formula unitSuch a neutral unit is called a formula unit

Ionic CompoundsIonic Compounds

Ionic CompoundsIonic Compounds

Recall that an atom of sodium has 1 valence Recall that an atom of sodium has 1 valence electron and a chlorine atom has 7 valence electron and a chlorine atom has 7 valence electronselectrons

When the two combine the sodium atom When the two combine the sodium atom transfers one electron to the chloride atomtransfers one electron to the chloride atom• As a result, both atoms now have full other energy As a result, both atoms now have full other energy

levels (they are stable)levels (they are stable)• This type of bonding (the transfer of electrons) is This type of bonding (the transfer of electrons) is

called ionic bondingcalled ionic bonding• Ionic bonds form between metals and non-metalsIonic bonds form between metals and non-metals

Ionic CompoundsIonic Compounds

Ionic BondingIonic Bonding

Ionic CompoundsIonic Compounds

Common properties of Ionic Common properties of Ionic CompoundsCompounds• Solid at room temperatureSolid at room temperature• Dissolve in waterDissolve in water• Solutions if ionic compounds conduct Solutions if ionic compounds conduct

electricityelectricity

Ionic CompoundsIonic Compounds

There are thousands of Ionic CompoundsThere are thousands of Ionic Compounds Several have common namesSeveral have common names They also have chemical namesThey also have chemical names

• See table A2.2 on page 41See table A2.2 on page 41 The state of an element or compounds is The state of an element or compounds is

indicated by a subscript: indicated by a subscript: (s)(s) for solid, for solid, (l)(l) for for liquid, liquid, (g)(g) for gas and for gas and (aq)(aq) for aqueous for aqueous• Aqueous is a compound or element dissolved Aqueous is a compound or element dissolved

in water in water

Naming Ionic CompoundsNaming Ionic Compounds

All names of ionic compounds have 2 All names of ionic compounds have 2 partsparts

• Every ionic compound is made up of a cation Every ionic compound is made up of a cation and an anionand an anion

The naming Rules work like this:The naming Rules work like this:1.1. Name the cation first by using the elementName the cation first by using the element’’s s

name. (it is usually a metal ion)name. (it is usually a metal ion)

2.2. Name the anion second by using the first part Name the anion second by using the first part of the elementof the element’’s name and changing the last s name and changing the last part to part to ““-ide-ide”” (it is usually a non-metal ion) (it is usually a non-metal ion)

Naming Ionic Compounds - Naming Ionic Compounds - ExampleExample

FormulaFormula CationCation AnionAnion NameName

NaClNaCl(s)(s) NaNa++ ClCl-- Sodium Sodium ChlorideChloride

BaFBaF22(s)(s) BaBa22 ++ FF-- Barium Barium fluoridefluoride

KK33NN(s)(s) K K ++ NN3-3- Potassium Potassium NitrideNitride

Formulas for Ionic CompoundsFormulas for Ionic Compounds

Contain element symbols that identify Contain element symbols that identify each type of ion presenteach type of ion present

In some formulas, the symbols are In some formulas, the symbols are followed by subscript numbers that followed by subscript numbers that indicated the ratio of ions in the compoundindicated the ratio of ions in the compound• For example in BaFFor example in BaF22(s) (s) there is one barium ion there is one barium ion

for every two fluoride ionsfor every two fluoride ions• This represents the formula unit (the smallest This represents the formula unit (the smallest

amount of the substance with the composition amount of the substance with the composition shown by the chemical formula)shown by the chemical formula)

Formulas for Ionic CompoundsFormulas for Ionic Compounds

All ionic compounds are composed of All ionic compounds are composed of an equal number of positive and an equal number of positive and negative charges. Cations = Anionsnegative charges. Cations = Anions

Example: NaClExample: NaCl• NaNa++ and Cl and Cl--, both charges cancel one , both charges cancel one

another out and therefore there is an another out and therefore there is an equal number of positive and negative equal number of positive and negative chargescharges

Formulas for Ionic CompoundsFormulas for Ionic Compounds All ionic compounds are composed of an All ionic compounds are composed of an

equal number of positive and negative equal number of positive and negative charges. Cations = Anionscharges. Cations = Anions

Example: AlClExample: AlCl3 3

• Each aluminium atom loses 3 electrons and each Each aluminium atom loses 3 electrons and each chloride atom gains 1chloride atom gains 1

• The aluminium ion has a charge of 3+ and the The aluminium ion has a charge of 3+ and the chloride ion has a charge of 1-chloride ion has a charge of 1-

• Therefore, every one aluminium ion combines with Therefore, every one aluminium ion combines with three chloride ionsthree chloride ions

• The ration is one cation (AlThe ration is one cation (Al3+3+) to three anions (Cl) to three anions (Cl--) ) and thus the formula, AlCland thus the formula, AlCl3 3

• See next slide with tableSee next slide with table

Formulas for Ionic CompoundsFormulas for Ionic Compounds

StepsSteps ExamplesExamples

Sodium Sodium chloridechloride

Aluminium Aluminium chloridechloride

1. Identify the ions 1. Identify the ions and their chargesand their charges

Sodium: NaSodium: Na++

Chloride: ClChloride: Cl--

Aluminium: AlAluminium: Al3+3+

Chloride: ClChloride: Cl--

2.Determine the total 2.Determine the total charges needed to charges needed to balancebalance

NaNa++ :1 :1

ClCl- - :1:1AlAl3+ 3+ :3:3

ClCl- - :1+1+1=3:1+1+1=3

3. Note the ratio of 3. Note the ratio of cations to anionscations to anions

1 to 11 to 1 1 to 31 to 3

4.Use subscripts to 4.Use subscripts to write the formula, if write the formula, if neededneeded

NaClNaCl AlClAlCl3 3

The Method of Lowest Common The Method of Lowest Common MultipleMultiple

Another way of determining the Another way of determining the correct formula for an ionic correct formula for an ionic compoundcompound• 11stst, find the lowest common multiple of , find the lowest common multiple of

the charges for the 2 ionsthe charges for the 2 ions• 22ndnd, divided by the combining capacity of , divided by the combining capacity of

one ion to get the correct subscript for one ion to get the correct subscript for that ionthat ion

• Example on board (copy)Example on board (copy)