Chapter 5 Molecules and Compounds (Part 2) · Chapter 5 Molecules and Compounds (Part 2) 2009,...

transcript

Roy Kennedy

Massachusetts Bay Community College

Wellesley Hills, MA

Introductory Chemistry, 3rd Edition

Nivaldo Tro

Chapter 5

Molecules and

Compounds (Part 2)

2009, Prentice Hall

5.6 Nomenclature: Naming

Compounds

• This will be on quiz 5

Tro's "Introductory Chemistry",

Chapter 5

Formula-to-Name

Step 1

Is the compound one of the

exceptions to the rules?

Chapter 5

Common Names—Exceptions

• H2O = Water, steam, ice.

• NH3 = Ammonia.

• CH4 = Methane.

• NaCl = Table salt.

• C12H22O11 = Table sugar.

Chapter 5

Formula-to-Name

Step 2

What major class of compound is it?

Ionic or Molecular?

Classifying Ionic or Molecular• Ionic compounds.

Metal + nonmetal(s) – Binary ionic

Type I cation – charge known

Type II cation – charge must be given

Compounds with polyatomic ions.

• Molecular compounds.

2 or more nonmetals.

Binary molecular (or binary covalent) 2 nonmetals..

Acids—Formula starts with H combined with a anion

either monoatomic or polyatomic ion.

Molecular when pure

Ionic when dissolved in water.

May be binary or oxyacid.

Chapter 5

Formula-to-Name

Step 3

What major subclass of compound is it?

Binary Ionic, Ionic with Polyatomic Ions,

Binary Molecular,

Binary Acid, or Oxyacid?

Chapter 5

Classifying Compounds

• Compounds containing a metal and a nonmetal = Binary ionic.

Type I and II.

• Compounds containing a polyatomic ion = Ionic with polyatomic ion.

• Compounds containing two nonmetals = Binary molecular compounds.

• Compounds containing H and a nonmetal = Binary acids.

• Compounds containing H and a polyatomic ion = Oxyacids.

Chapter 5

Formula-to-Name

Step 4

5.7 Ionic Compounds

5.8 Molecular Compounds

5.9 Acids – Molecular compounds that behave

like ionic compounds in water

5.7 Naming Ionic Compounds

Chapter 5

Types of Ionic Compounds

• Monoatomic cation (metal) and

monoatomic anion (nonmetal)

Cations with only one charge – Type I – Main

group and Ag+ and Zn2+

Cations with more than one charge – Type II –

usually transition metals and some heavier main

group elements

• Polyatomic ion present (KNOW THE

POLYATOMIC IONS FROM THE WEB)Tro's "Introductory Chemistry",

Chapter 5

Formula-to-Name

Rules for Ionic

• Made of cation and anion.

• Name by simply naming the ions.

If cation is:

Type I metal = Metal name.

Type II metal = Metal name (charge).

Polyatomic ion = Name of polyatomic ion.

If anion is:

Nonmetal = Stem of nonmetal name + -ide.

Polyatomic ion = Name of polyatomic ion.

Chapter 5

Monatomic Nonmetal Anion• Charge from periodic table

• To name anion, take the root of the element

name and add the suffix–ide.

• Group 5A Group 6A Group 7A

N3- nitride O2- oxide F- fluoride

P3- phosphide S2- sulfide Cl- chloride

Br- bromide

I- iodide

Chapter 5

Metal Cations• Type I

one possible charge.

1A, 2A, (Al, Zn, Ag).

Charge by position on the periodic table.

1A = +, 2A = 2+, Al = 3+.

Some need to be memorized.

Zn = 2+, Ag = +.

• Type II

Metals whose ions can have more than one possible charge.

Determine charge by charge on anion.

Chapter 5

Type I Binary Ionic Compounds

Formula Cation name Anion name

CaF2 calcium fluoride

K2S potassium sulfide

NaBr sodium bromide

Al2S3 aluminum sulfide

MgO magnesium oxide

Note: no numerical prefixes are used.

Chapter 5

Type II Binary Ionic Compounds

• Cation name (charge as Roman numeral) + anion

• Charge is determined from anion

Determining the Charge on a Variable

Charge Cation—NiCl2 and Fe2S3

1. Ni?+ + 2 Cl-

2. The Ni charge must balance the anions total 2 x (-1) = -2

3. Ni is 2+ nickel(II)chloride

1. Fe2S3 2Fe?+ + 3 S2-

2. The Fe charge balances the anions. 3 x (-2) = =6

3. Fe is 3+, 2 x (+3) = 6 iron(III)sulfide

Another way to work out the

charge• Reverse the method of crossing the charges

Cu2O Cu21+ O 2- copper(I)oxide

Be careful because a common factor may have

been divided out

PbO2 – uncrossing the charges leads to Pb2+ and

O - -, but O is actually O2- . Two O2- is -4

This compound is actuall Pb 4+ lead(IV)oxide

Chapter 5

Compounds Containing

Polyatomic Ions

• Name of cation Type I or Type II rules. + name

of anion.

The polyatomic ions you need to

know are on the stuff you must

memorize web page

Stuff you must memorize

Chapter 5

Writing Names for an Ionic Compound Containing

Polyatomic Ion,

Iron(III) phosphate

Chapter 5

Type I

NaNO2 sodium nitrite

Ca(NO3) 2 calcium nitrate

Al2(PO4) 3 aluminum phosphate

Type II

Pb(ClO4) 2 lead(II)perchlorate 2 ClO4- means Pb is 2+

CuSO4 copper (II)sulfate 1 SO42- means Cu is 2+

Fe2(PO4) 3 iron(III) phosphate 2 PO43- means Fe is 3+

5.8 Naming Molecular

Compounds

Chapter 5

Formula-to-Name

Rules for Molecular

• Only for 2 elements binary.

• For binary molecular:

numerical first numerical root

Prefix + element + prefix + second + -ide

(omit if 1) name element

Chapter 5

Numerical Prefixes

• 1 = mono-

Not used on first nonmetal.

• 2 = di-

• 3 = tri-

• 4 = tetra-

• 5 = penta-

• 6 = hexa-

• Drop last ―a‖ if name begins with vowel.

Binary Molecular Compounds

of Two Nonmetals

• SO3 sulfur trioxide

• CS2 carbon dioxide

• S4N4 tetrasulfur tetranitride

• SF6 sulfur hexafluoride

• P2O5 diphosphorus pentaoxide

5.9 Naming Acids

Chapter 5

Formula-to-Name

Acids• Acids have formulas that start with H and contain

an anion either monoatomic or polyatomic

• Acids are molecular, but when dissolved in water they for ions H+ cation(s) and an anion(s).

Binary acids monoatomic ion

• Hydro- prefix + stem of the name of the nonmetal + -ic suffix + acid.

HCl hydrochloric acid

HBr hydrobromic acid

HI hydroiodic acid

Chapter 5

Polyatomic ion acid• Oxyacids:

If polyatomic ion ends in –ate = Name of polyatomic ion with –ic suffix + acid.

If polyatomic ion ends in –ite = Name of polyatomic ion with –ous suffix + acid.

Acid anion name

HNO3 nitrate nitric acid

H2SO3 sulfite sulfurous acid

HClO4 perchlorate perchloric acis

H2CrO4 chromate chromic acid

H3PO4 phosphate phosphoric acid

H3PO3 phosphite phosphorus acid

Naming compounds from formula

• Decide if common name

• Classify as Ionic or Molecular

• Ionic –

Type I or II cation

Monoatomic or polyatomic ion

• Molecular

Binary

OxyacidsTro's "Introductory Chemistry",

Chapter 5

Naming examples

• Ca(ClO4)2 calcium perchlorate

• NH3 ammonia

• P4S5 tetraphosphorous pentasulfide

• HClO3 chlorous acid

• Na2S sodium sulfide

• CoCl3 cobalt(III)chloride

• HBr hydrobromic acid

Chapter 5

5.10 Nomenclature Summary

• An excellent summary of naming

compounds is Figure 5.17 on page 143.

Chapter 5

Chapter 5 Molecules and Compounds (Part 2) · Chapter 5 Molecules and Compounds (Part 2) 2009,...

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