naming binary compounds containing a metal and a nonmetal pisgah high school m. jones

Naming Binary Naming Binary Compounds Compounds

Containing a Metal Containing a Metal and a Nonmetaland a Nonmetal

Pisgah High SchoolPisgah High SchoolM. JonesM. Jones

The Stock SystemThe Stock System

Add a Roman numeral after Add a Roman numeral after the name of the metal to the name of the metal to

indicate the oxidation number.indicate the oxidation number.

Named for Alfred Stock, a Named for Alfred Stock, a German chemist and teacher who German chemist and teacher who published the system in 1919.published the system in 1919.

Using the Stock System:Using the Stock System:

1.1. Write the name of the metalWrite the name of the metal

2.2. Add a Roman numeral Add a Roman numeral corresponding to the oxidation corresponding to the oxidation number of the metal (if necessary)number of the metal (if necessary)

3.3. Write the name of the negative Write the name of the negative element, modified to end in -element, modified to end in -ideide

When is the Roman Numeral When is the Roman Numeral Necessary?Necessary?

In addition, omit the Roman numeral In addition, omit the Roman numeral for Al, Ga, In, Zn, Cd and Ag.for Al, Ga, In, Zn, Cd and Ag.

Metals in groups IA, IIA, and III B Metals in groups IA, IIA, and III B do not need Roman numerals.do not need Roman numerals.

When the metal has more than one When the metal has more than one oxidation number.oxidation number.

What is an oxidation number?What is an oxidation number?

The oxidation number is a The oxidation number is a number that tells us how an number that tells us how an element combines with other element combines with other elements.elements.

For ions, the For ions, the oxidation number is oxidation number is

the ionic charge.the ionic charge.

What does the Roman Numeral do?What does the Roman Numeral do?

Consider: FeO and FeConsider: FeO and Fe22OO33

Both contain iron and oxygenBoth contain iron and oxygenBut, both cannot be But, both cannot be iron oxideiron oxide … …

The Roman numeral indicates the The Roman numeral indicates the oxidation number on a single metal oxidation number on a single metal atom, and differentiates between atom, and differentiates between several possible compounds.several possible compounds.

What does the Roman Numeral do?What does the Roman Numeral do?

Consider: FeO and FeConsider: FeO and Fe22OO33

Both contain iron and oxygenBoth contain iron and oxygenBut, both cannot be But, both cannot be iron oxideiron oxide … …

Therefore…Therefore…

FeO is called iron(II) oxide and FeO is called iron(II) oxide and

FeFe22OO33 is called iron(III) oxide. is called iron(III) oxide.

First, determine the oxidation First, determine the oxidation number of iron in FeO …number of iron in FeO …

… … by starting with the negative by starting with the negative element, find the oxidation number element, find the oxidation number

of the positive element.of the positive element.

Since iron has an oxidation Since iron has an oxidation number of +2, FeO is namednumber of +2, FeO is named

iron(II) oxide.iron(II) oxide.

First, determine the oxidation number First, determine the oxidation number of iron in Feof iron in Fe22OO33 … …

… … by starting with the negative by starting with the negative element, find the oxidation element, find the oxidation

number of the positive element.number of the positive element.

Since iron’s oxidation number is +3, Since iron’s oxidation number is +3, FeFe22OO33 is named is named

Then for FeThen for Fe22OO33……

iron(III) oxide.iron(III) oxide.

Remember …Remember …

You need not use a Roman You need not use a Roman numeral for metals in groups numeral for metals in groups

IA, IIA and IIIA, IA, IIA and IIIA,

or for Al, Ga, In, Zn, Cd or Agor for Al, Ga, In, Zn, Cd or Ag

The Roman numeral indicates the The Roman numeral indicates the oxidation number of the metal.oxidation number of the metal.

Name these compounds:Name these compounds:

SrO SrO

CrClCrCl33

ZnSZnS

MnMn22OO33

SnFSnF44

TiSTiS22

Srontium oxide Srontium oxide

Chromium(III) chloride Chromium(III) chloride

Zinc sulfideZinc sulfide

Manganese(III) oxideManganese(III) oxide

Sin(IV) fluoride Sin(IV) fluoride

Titanium(IV) sulfideTitanium(IV) sulfide

Writing formulas for Writing formulas for binary compounds of a binary compounds of a metal and a nonmetalmetal and a nonmetal

The sum of the oxidation numbers The sum of the oxidation numbers on all the atoms in a compound on all the atoms in a compound must equal zero.must equal zero.

FeOFeO+2 –2 = 0+2 –2 = 0

Consider iron(II) oxide. Consider iron(II) oxide.

The sum is 0.The sum is 0.

Oxygen is –2 Oxygen is –2 and iron is +2.and iron is +2.

Now consider iron(III) oxideNow consider iron(III) oxide

FeFe22OO33

+3 -2+3 -2

In iron(III) oxide, In iron(III) oxide, the iron is +3 and the iron is +3 and the oxygen is –2. the oxygen is –2.

These don’t add up to zero.These don’t add up to zero.

Now consider iron(III) oxideNow consider iron(III) oxide

FeFe22OO33

+3 -2+3 -2+6+6 -6-6 = 0= 0

But, since there But, since there are two Fe atoms are two Fe atoms

and three O atoms, and three O atoms, we can multiply to we can multiply to

get the totals.get the totals.2 x 3 = 62 x 3 = 6

3 x –2 = -63 x –2 = -6 Now the sum is Now the sum is zero.zero.

Look at it another way:Look at it another way:

FeFe22OO33 = = Fe FeFe Fe O O OO O O+3+3 +3+3 -2-2 -2-2 -2-2

+6+6 -6-6+6 +6 –6–6 == 00

Now you are ready to Now you are ready to write formulaswrite formulas

The Crisscross MethodThe Crisscross Method

Be aware of the potential Be aware of the potential problems with this problems with this method.method.

……most of the time.most of the time.Simple but effective… Simple but effective…

Suppose you are writing the formula Suppose you are writing the formula for copper(II) chloridefor copper(II) chloride

First, write down First, write down the symbolsthe symbols::

CuCu ClCl

Then write the oxidation numbers in Then write the oxidation numbers in copper(II) chloridecopper(II) chloride

CuCu ClCl

The oxidation The oxidation number of number of copper comes copper comes from the from the name.name.

-1-1+2+2

Get the Get the oxidation oxidation

number of number of chlorine chlorine from the from the

periodic table.periodic table.

Crisscross the numbers for the Crisscross the numbers for the formula of copper(II) chlorideformula of copper(II) chloride

CuCu ClCl+2+2 -1-1

2211

When you crisscross, When you crisscross, ignore the signs.ignore the signs.

11

Clean up the subscripts in the Clean up the subscripts in the formula of copper(II) chlorideformula of copper(II) chloride

CuCu ClCl+2+2 -1-1

22

Subscripts of 1 are invisible. Subscripts of 1 are invisible. (don’t even put the 1)(don’t even put the 1)

CuCu

Clean up the subscripts in the Clean up the subscripts in the formula of copper(II) chlorideformula of copper(II) chloride

ClCl+2+2 -1-1

22

Subscripts of 1 are invisible. Subscripts of 1 are invisible. (don’t even put the 1)(don’t even put the 1)

Now you have the formula of Now you have the formula of copper(II) chloridecopper(II) chloride

CuCu ClCl22

When is the “crisscross When is the “crisscross method” a problem?method” a problem?

When all the subscripts When all the subscripts are divisible by a number are divisible by a number

other than 1.other than 1.

Look at chromium(VI) oxideLook at chromium(VI) oxide

CrCr OOOxygen is Oxygen is always -2always -2

-2-2+6+6

The The oxidation oxidation number number of Cr is of Cr is +6+6

CrCr OO


+6+6 -2-2

6622

When you crisscross, both When you crisscross, both subscripts are divisible by 2.subscripts are divisible by 2.

Now, crisscross the oxidation Now, crisscross the oxidation numbers.numbers.

CrCr____ 22

____ 22


+6+6 -2-2

Divide each subscript by 2.Divide each subscript by 2.

OO6622

OO


33

This is the correct formulaThis is the correct formula

Remember, 1’s are invisible.Remember, 1’s are invisible.

CrCr

Remember: reduce the Remember: reduce the subscripts to their smallest subscripts to their smallest

whole-number values.whole-number values.

Unless there’s a really Unless there’s a really good reason not to.good reason not to.

Some Exceptions:Some Exceptions:

NN22OO44

HgHg22ClCl22

CC22HH66

CC66HH66

HH22OO22

PP44OO1010

The “ic/ous” SystemThe “ic/ous” System

The “ic/ous” method …The “ic/ous” method …

… … uses prefixes like uses prefixes like hypo-hypo- & & per-per-

… … may use the Latin namemay use the Latin name

… … uses the uses the –ic–ic or – or –ousous suffixes suffixes on the name of the metal.on the name of the metal.

… … is an archaic method, but still in is an archaic method, but still in use today by the chemical industryuse today by the chemical industry

ICICOUSOUS

Higher oxidation numberHigher oxidation number

Lower oxidation numberLower oxidation number

Use “ic” for the Use “ic” for the higher oxidation higher oxidation number, like number, like ferric.ferric. Use “ous” for the Use “ous” for the

lower oxidation lower oxidation number, like number, like

ferrous.ferrous.

Name and Name and

Latin RootLatin Root

Lower Ox. Lower Ox. NumberNumber

Higher Ox. Higher Ox. NumberNumber

iron iron

ferrumferrum

ferrous ferrous

Fe Fe 2+2+

ferric ferric

FeFe3+3+

copper copper

cuprumcuprum

cuprous cuprous

CuCu++

cupric cupric

CuCu2+2+

mercurymercury mercurous mercurous

HgHg222+2+

mercuric mercuric

HgHg2+2+

ExamplesExamples … …

FeClFeCl22

CuOCuOFeNFeN

CuCu33PP

HgSHgS

HgHg22ClCl22

Ferrous chlorideFerrous chlorideCupric oxideCupric oxideFerric nitrideFerric nitrideCuprous phosphideCuprous phosphideMercuric sulfideMercuric sulfideMercurous chlorideMercurous chloride

Write the formula …Write the formula …

Ferric bromideFerric bromideCupric nitrideCupric nitrideFerrous chlorideFerrous chlorideMercuric oxideMercuric oxideMercurous iodideMercurous iodideStannous fluorideStannous fluoride

FeBrFeBr33

CuCu33NN22

FeClFeCl22

HgOHgO

HgHg22II22

SnFSnF22

naming binary compounds containing a metal and a nonmetal pisgah high school m. jones

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