1 Ions combine to form ionic compounds. Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion) Properties of ionic compounds

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• Ions combine to form ionic compounds.

• Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion)

• Properties of ionic compounds High melting points Conduct electricity

If meltedIf dissolved in water

Section 4.11

Compounds That Contain Ions

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• Ionic compounds are electrically neutral.• The charges on the anions and cations in the

compound must sum to zero.

Section 4.11


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• Write the cation element symbol followed by the anion element symbol.

• The number of cations and anions must be correct for their charges to sum to zero.

Formulas for Ionic Compounds

Section 4.11


Na +1 + Cl-1 NaCl

Cation charge anion charge Compound net charge +1 + -1 = 0

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• Write the cation element symbol followed by the anion element symbol.

• The number of cations and anions must be correct for their charges to sum to zero.

Formulas for Ionic Compounds

Section 4.11


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Concept Check

A compound contains an unknown ion X and has the formula XCl2. Ion X contains 20 electrons. What is the identity of X?

a) Ti2+

b) Sc+

c) Ca2+ d) Cr2+

Section 4.11


Z = # of e- + positive chargeor

Z = # of e- - negative charge

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Concept Check

A member of the alkaline earth metal family whose most stable ion contains 36 electrons forms a compound with bromine. What is the correct formula for this compound?

a) CaBr2

b) KrBrc) RbBr

d) SrBr2

Section 4.11


• Ionic compounds are electrically neutral.

• The charges on the anions and cations in the compound must sum to zero.

Copyright©2004 by Houghton Mifflin Company. All rights

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Introductory Chemistry: A Foundation

FIFTH EDITION

by Steven S. ZumdahlUniversity of Illinois


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Nomenclature

Chapter 5


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Naming of Compounds

• Naming of compounds has long been necessary to identify something

• Names originally based upon “common names”

– Common name Stock system name– Epsom salts Magnesium chloride– Gypsum Calcium sulfate– Blue vitriol Copper (II) sulfate– Calomel Mercury (I) chloride– Saltpeter Potassium nitrate– Quicklime calcium oxide– Caustic soda sodium hydroxide

An ancient painting showing Romans drinking wine.


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Sugar of Lead

• Boiling of wine produced a thick, sweet liquid which was used as a sweetener.

• Actually contained lead acetate – Pb(C2H3O2)2

– Thought to have lead to the downfall of the Roman empire due to lead poisoning (in addition to lead water pipes)

– Lead poisoning causes lethargy and mental illness


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Problems• These common names were impractical

– Worldwide communication problems– 4 million compounds– We needed a system to “systematically” name

all of these compounds, you wouldn’t have to memorize each name to know what it was.

– If you learn the system, you will be able to name a compound from its formula and vice versa


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Common Names - Exceptions• Common names still in use today……..

• H2O = water, steam, ice

• NH3 = ammonia

• CH4 = methane

• NaCl = table salt

• C12H22O11 = table sugar

• CaSO4•2H2O=plaster of paris


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An artist using plaster of Paris, a gypsum plaster.

Source: Bob Daemmrick/The Image Works

Chemical names and Formulas• There are three types of ionic compounds to write

formulas for and name

o Binary ionic compound (Type I)o Transition metal compound (Type II)o Ionic compound containing polyatomic ions

• Covalent compounds have a different naming system

It uses prefixes

• Acids

5.1 Naming Compounds

• Binary ionic compounds are made up of only 2 different elements

o There can be more than 2 or more atoms

though

NaCl K2O Al2S3


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5.2 Naming CompoundsBinary Type I and II


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Classifying Binary Compounds

• Compounds containing a metal and a nonmetal are binary ionic– Type I and II

• Compounds containing two nonmetals are Covalent– Type III

• Compounds containing H and a nonmetal = Acids


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Metal Cations• Type I

– Metals that can only have one possible charge– Determine charge by position on the Periodic

Table• Type II

– Metals that can have more than one possible charge

– Determine metal cation’s charge from the charge on anion


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• To name a binary ionic compound Write the name of the cation first (always a metal) Next, write the name of the anion, but change the

ending to –ide Note that any subscripts do not change the name

NaCl

sodium

chlorine → chloride

sodium chloride

Type I Binary Ionic Compounds


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Examples

• KCl

• MgBr2

• SrO

• Al2O3

• Rb3N

• KI

potassium chloride

magnesium bromide

strontium oxide

aluminum oxide

rubidium nitride

potassium iodide

•Write formulas for the following compoundsoSodium sulfide

oPotassium iodide

oCalcium bromide

oAluminum oxide

oRubidium selenide

o Na2S

o KI

o CaBr2

o Al2O3

o Rb2S


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Type II Binary Ionic Compounds• Contain Metal Cation + Nonmetal Anion

o Transition metals can have various oxidation numbers or charges

For example iron can be either Fe2+ or Fe3+

• Metal cation name is the metal name followed by a Roman Numeral in parentheses to indicate its charge– Determine charge on metal from anion charge– Common Type II cations in Table 5.2

¶ Nonmetal anion named by changing the ending on the nonmetal name to -ide


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Examples

• FeS

• Fe2S3

• Cu2O

• CuO

• PbCl2

• PbCl4

• Hg2Se

iron (II) sulfide

iron (III) sulfide

copper (I) oxide

copper (II) oxide

lead (II) chloride

lead (IV) chloride

mercury (II) selenide

ferrous sulfide

ferric sulfide

cuprous oxide

cupric oxide

plumbous chloride

plumbic chloride

mercuric selenide

Systematic Name Latin Name


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• Polyatomic ions are ions that contain more than one atom

o (SO4)2-

o (OH)-

o (PO4)3-

o (NH4)+

• It is important to note that the charge is distributed throughout all the atoms in the ion

o Not only on the last atom

5.5 Naming Polyatomic ions


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Polyatomic Ions to be memorized!

• Carbonate CO32-

• Nitrate NO31-

• Phosphate PO43-

• Chlorate ClO31-

• Bromate BrO31-

• Sulfate SO42-

• Hydroxide OH1-

• Ammonium NH41+


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Patterns for Polyatomic Ions

• -ate ion– chlorate = ClO3

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• -ate ion plus 1 O same charge, per- prefix– perchlorate = ClO4

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• -ate ion minus 1 O same charge, -ite suffix– chlorite = ClO2

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• -ate ion minus 2 O same charge, hypo- prefix, -ite suffix– hypochlorite = ClO-


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5.3 Naming CompoundsBinary Type III


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Type III - Binary Compounds of 2 Nonmetals


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Prefixes

• Drop last “a” in the prefix if the name begins with vowel

octa-8

hepta-7

hexa-6

penta-5

tetra-4

tri-3

di-2

mono-

(not used on first nonmetal)

1

PrefixSubscript


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Examples

• CO

• CO2

• BF3

• N2O5

• NO

• CCl4

• NO2

carbon monoxide

carbon dioxide

boron trifluoride

dinitrogen pentoxide

nitrogen monoxide

carbon tetrachloride

nitrogen dioxide


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A mix of types

• Na2O LiF

• N2O6 SnO

• H2O HgS

• Mg3P2 CoN

• CuF NCl3

• CrCl3 CS2


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Copper (II) sulfate crystals.


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5.6 Naming Acids and Bases

Bases

• Bases (ending in OH-) are named as taught before

A common base with a different name is NH3 (ammonia)


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Acids

• Contain H+ cation and anion

• Binary acids have H+ cation and a nonmetal anion

• Oxy (Ternary) acids have H+ cation and a polyatomic anion

• Try HI –

HF -


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Rules for Naming Acids cont.

• When anion contains oxygen (oxyanion) the root name of the anion is used, along with– ic acid for oxyanions ending in –ate– ous acid for oxyanions ending in –ite

– H2SO4 sulfate ion Sulfur ic acid– HNO3 nitrate ion Nitr ic acid– HNO2 nitrite ion Nitr ous acid


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Other examples

HClO hypochlorite ion hypochlorous acid HClO2 chlorite ion chlorous acid HClO3 chlorate ion chloric acid

HClO4 perchlorate ion perchloric acid

• HIO4 ?????!!!!!!


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5.7 Writing Formulas from Names


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Writing the Formulas from the Names

• For Type III compounds, use the prefixes to determine the subscripts

• For Type I, Type II, polyatomic Compounds and Acids– Determine the ions present– Determine the charges on the cation and anion– Balance the charges to get the subscripts


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Figure 5.3: A flow chart for naming acids. The acid is considered as one or

more H+ ions attached to an anion.

Documents

1 Ions combine to form ionic compounds. Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion) Properties of ionic compounds