Ionic Compounds: Names and Formulas

Ionic Ionic Compounds:Compounds:Names and Names and FormulasFormulasSNC2DSNC2D

Counting IonsCounting Ions

Sodium chloride or NaCl Sodium chloride or NaCl contains 1 sodium ion and 1 chloride contains 1 sodium ion and 1 chloride ion.ion.

(Lewis dot diagrams)(Lewis dot diagrams)

Counting IonsCounting Ions

However, different ions may form However, different ions may form compounds in different ratios. compounds in different ratios.

For example, calcium chloride or CaClFor example, calcium chloride or CaCl22

contains 1 calcium ion and 2 chloride ions.contains 1 calcium ion and 2 chloride ions.

(Subscripts are added to the symbols in a (Subscripts are added to the symbols in a formula if there is more than one of that formula if there is more than one of that type of atom.)type of atom.)

Counting Ions: PracticeCounting Ions: Practice

FeClFeCl33

NaNa22O O

CaOCaO

FeFe22OO33

NaClONaClO33

NaNa22COCO33

Ca(ClOCa(ClO33))22


FeClFeCl33 containscontains 1 iron ion and 3 chloride ions1 iron ion and 3 chloride ions

NaNa22O O

CaOCaO

FeFe22OO33

NaClONaClO33

NaNa22COCO33

Ca(ClOCa(ClO33))22



NaNa22O containsO contains 2 sodium ions and 1 oxide ion2 sodium ions and 1 oxide ion

CaOCaO

FeFe22OO33

NaClONaClO33

NaNa22COCO33

Ca(ClOCa(ClO33))22




CaOCaO containscontains 1 calcium ion and 1 oxide ion1 calcium ion and 1 oxide ion

FeFe22OO33

NaClONaClO33

NaNa22COCO33

Ca(ClOCa(ClO33))22





FeFe22OO33 contains contains 2 iron ions and 3 oxide ions2 iron ions and 3 oxide ions

NaClONaClO33

NaNa22COCO33

Ca(ClOCa(ClO33))22






NaClONaClO33 contains contains 1 sodium ion and 1 chlorate ion1 sodium ion and 1 chlorate ion

NaNa22COCO33

Ca(ClOCa(ClO33))22







NaNa22COCO33 contains contains 2 sodium ions and 1 carbonate ion2 sodium ions and 1 carbonate ion

Ca(ClOCa(ClO33))22







NaNa22COCO33 contains contains 2 sodium ions and 1 carbonate ion2 sodium ions and 1 carbonate ion

Ca(ClOCa(ClO33))22 contains contains 1 calcium ion and 2 chlorate 1 calcium ion and 2 chlorate

ionsions

Why These Ratios?Why These Ratios?

It is the valence electrons that It is the valence electrons that determine how these ions combine.determine how these ions combine.

For example, calcium had 2 valence For example, calcium had 2 valence electrons to lose and each chlorine electrons to lose and each chlorine only wants 1. So calcium has to find only wants 1. So calcium has to find 2 chlorines.2 chlorines.

Ratio PracticeRatio Practice

Use diagrams to determine how the Use diagrams to determine how the following combine to form following combine to form compounds:compounds:

MgMg2+2+ and Br and Br1-1-

LiLi1+1+ and P and P3-3-

CaCa2+2+ and O and O2-2-

AlAl3+3+ and OH and OH1-1-

KK1+1+ and SO and SO442-2-



MgMg2+2+ and Br and Br1-1- MgBrMgBr22

LiLi1+1+ and P and P3-3-







LiLi1+1+ and P and P3-3- LiLi33PP








CaCa2+2+ and O and O2-2- CaOCaO








AlAl3+3+ and OH and OH1-1- Al(OH)Al(OH)33







AlAl3+3+ and OH and OH1-1- Al(OH)Al(OH)33

KK1+1+ and SO and SO442-2- KK22SOSO44



AlAl3+3+ and O and O2-2- AlAl22OO33

Notice that the quick method of Notice that the quick method of determining the formula is to criss-determining the formula is to criss-cross the valences:cross the valences:

Criss-crossCriss-cross

But the ratio between the ions must But the ratio between the ions must be reduced to lowest terms (and 1s be reduced to lowest terms (and 1s are not written).are not written).

E.g. PbE.g. Pb4+4+ and O and O2-2- becomes becomes

?? notnot Pb Pb22OO44

Criss-crossCriss-cross

But the ratio between the ions must be But the ratio between the ions must be reduced to lowest terms (and 1s are not reduced to lowest terms (and 1s are not written).written).

E.g. PbE.g. Pb4+4+ and O and O2-2- becomes becomes

PbOPbO22 notnot Pb Pb22OO44

Please complete “More Formula Practice.”Please complete “More Formula Practice.”

Ionic Compounds: NamesIonic Compounds: Names

The name of an ionic compound is The name of an ionic compound is simply the name of the positive ion simply the name of the positive ion followed by the name of the negative followed by the name of the negative ion, e.g.:ion, e.g.:

NaClNaCl

CaClCaCl22

LiLi22O O



NaClNaCl is is sodium chloridesodium chloride

CaClCaCl22

LiLi22O O




CaClCaCl22 is is calcium chloridecalcium chloride

LiLi22OO




CaClCaCl22 is is calcium chloridecalcium chloride

LiLi22O O is is lithium oxidelithium oxide



KOHKOH

Mg(ClOMg(ClO33))22

NHNH44F F



KOHKOH is is potassium hydroxidepotassium hydroxide

Mg(ClOMg(ClO33))22

NHNH44F F


The name of an ionic compound is simply The name of an ionic compound is simply the name of the positive ion followed by the name of the positive ion followed by the name of the negative ion, e.g.:the name of the negative ion, e.g.:


Mg(ClOMg(ClO33))22 is is magnesium chloratemagnesium chlorate

NHNH44F F


The name of an ionic compound is simply The name of an ionic compound is simply the name of the positive ion followed by the name of the positive ion followed by the name of the negative ion, e.g.:the name of the negative ion, e.g.:


Mg(ClOMg(ClO33))22 is is magnesium chloratemagnesium chlorate

NHNH44F F is is ammonium fluorideammonium fluoride

Names with Multivalent Names with Multivalent IonsIons

The only tricky ones to name are those The only tricky ones to name are those that contain multivalent ions. It is that contain multivalent ions. It is necessary to look at how the ions have necessary to look at how the ions have combined to figure out the valence of the combined to figure out the valence of the multivalent ion.multivalent ion.

FeOFeO must bemust be

FeFe22OO33 must bemust be


The only tricky ones to name are those The only tricky ones to name are those that contain multivalent ions. It is that contain multivalent ions. It is necessary to look at how the ions have necessary to look at how the ions have combined to figure out the valence of the combined to figure out the valence of the multivalent ion.multivalent ion.

FeOFeO must bemust be iron (II) oxideiron (II) oxide

(because oxide is O(because oxide is O2-2-))

FeFe22OO33 must bemust be


The only tricky ones to name are those that The only tricky ones to name are those that contain multivalent ions. It is necessary to contain multivalent ions. It is necessary to look at how the ions have combined to figure look at how the ions have combined to figure out the valence of the multivalent ion.out the valence of the multivalent ion.

FeOFeO must bemust be iron (II) oxideiron (II) oxide

(because oxide is O(because oxide is O2- 2- and the ratio is 1:1)and the ratio is 1:1)

FeFe22OO33 must bemust be iron (III) oxideiron (III) oxide


Try it with copper:Try it with copper:

CuClCuCl22

CuSOCuSO44

CuCu22OO



CuClCuCl22 copper (II) chloridecopper (II) chloride

CuSOCuSO44

CuCu22OO




CuSOCuSO44 copper (II) sulphatecopper (II) sulphate

CuCu22OO




CuSOCuSO44 copper (II) sulphatecopper (II) sulphate

CuCu22OO copper (I) oxidecopper (I) oxide

More PracticeMore Practice

Please complete Please complete the “More the “More Practice” Practice” handout and handout and textbook textbook questions p. questions p. 171 #6-8.171 #6-8.

Ionic Compounds: Names and Formulas

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