Chapter 4

Ionic Compounds

Chemical Bonds

• 2-types of bonding are found in compounds– Ionic bond – Chapter 4– Covalent bond – Chapter 5

Ions

• Ionic compounds – substances comprised of ions of a metal combined with ions of a nonmetal or group of non-metals

Ions

• Metals– Lose electrons– Forms a cation

• Nonmetals– Gain electrons– Forms an anion

Ions and the Octet Rule

• Stated– Metals form cations– Nonmetals form anions

• Why?– An ion is formed so that the atom achieves noble gas

configuration• Octet Rule – main group elements tend to undergo reactions

that leave them with 8 electrons in outer shell– Outer shell – valence shell – highest period #

– Outer electrons – valence electrons – e- in highest period #

Electron-Dot Symbols

• Electron-dot symbol – An atomic symbol with dots placed around it to indicate the number of valence electrons

Periodic Properties and Ion Formation

• Ease by which an element forms a cation or anion is determined by the energy involved

Periodic Properties and Ion Formation

• Ease by which a cation is formed – ionization energy– Metals have lower ionization energies than nonmetals– Ionization energy increases across a period– Ionization energy decreases down a group

Periodic Properties and Ion Formation

• Ease by which an anion is formed – electron affinity– Nonmetals have larger electron affinities– Electron affinity values become more negative

across a group– Electron affinity values become less negative

down a group

Ionic Bond

• Ionic bond – the glue that holds the metal and nonmetal together– Electrostatic attraction (magnets) – occurs when

opposites attract

Some Properties of Ionic Compounds

• Usually crystalline• Ions in a solid do not move – do not conduct

electricity• Once dissolved – ions move freely and conduct

electricity• High melting and boiling points• Ionic solids shatter if struck hard• Ionic compounds dissolve in water if the

attraction of ions to water is greater than the ions attraction to each other

Ionic Bonds

Problem

• Which of the following ions occurs commonly? 

– A.  N3+

– B.  S6+

– C.  O2-

– D.  Ca+

– E.  Cl+

Problems

• Which of the following ions occurs commonly? 

– A.  P3+

– B.  Br7+

– C.  O6+

– D.  Ca2+

– E.  K-

Ionic Bonds

Naming Ions

• Group 1A, Group 2A, Al, Ga, In, Zn, Sc, Ag, Cd, Ru ions– Give name of element followed by word ion

• All other metals– Give name of element + charge in parenthesis (roman

numerals) followed by word ion

• Element anions– Replace the ending of the element name with -ide

Polyatomic Ions

• Polyatomic ion– Poly – many– Atomic – atom– Ion – ion

• Think of them as a chemical unit– States which atoms are present, exact #

atoms present and the charge

Polyatomic Ions

Problem

• Which one of the following combinations of names and formulas of ions is incorrect? 

– A.  O2- oxide

– B.  Al3+ aluminum

– C.  NO3- nitrate

– D.  PO43- phosphate

– E.  CrO42- chromate

Problem

• Which one of the following combinations of names and formulas of ions is incorrect? 

– A.  O2- oxide– B.  Cd2+ cadmium

– C.  ClO3- chlorate

– D.  HCO3- hydrogen carbonate

– E.  NO2- nitrate

Problem

• Which one of the following combinations of names and formulas of ions is incorrect? 

– A.  Ba2+ barium– B.  S2- sulfate– C.  CN- cyanide

– D.  ClO4- perchlorate

– E.  HCO3- bicarbonate

Naming Ionic Compounds

• Simply combine the names previously discussed in naming ions without the word ion

• Determine which element is the cation– Can the cation only have one possible charge

• Yes– Give the name of the metal as seen on periodic table– Give the anion the root name of the element followed

by the ending –ide• Polyatomic ions – get their name

Naming Ionic Compounds

• No– Give the name of the metal as seen on

periodic table– Indicate the charge on the metal

• Use roman numerals in parenthesis

– Give the anion the root name of the element followed by the ending –ide

• Polyatomic ions – get their name

Problem

• The colorless substance, MgF2, is used in the ceramics and glass industry. What is its name? 

– A.  magnesium difluoride– B.  magnesium fluoride– C.  magnesium(II) fluoride– D.  monomagnesium difluoride– E.  none of these choices is correct, since they are all

misspelled

Problem

• The compound, BaO, absorbs water and carbon dioxide readily and is used to dry gases and organic solvents. What is its name? 

– A.  barium oxide– B.  barium(II) oxide– C.  barium monoxide– D.  baric oxide– E.  barium peroxide

Problem

• The substance, CoCl2, is useful as a humidity indicator because it changes from pale blue to pink as it gains water from moist air. What is its name? 

– A.  cobalt dichloride– B.  cobalt(II) chloride– C.  cobalt chloride– D.  cobaltic chloride– E.  copper(II) chloride

Problem

• A red glaze on porcelain can be produced by using MnSO4. What is its name? 

– A.  manganese disulfate– B.  manganese(II) sulfate– C.  manganese(IV) sulfate– D.  manganese sulfate– E.  manganese(I) sulfate

Problem

• The substance, KClO3, is a strong oxidizer used in explosives, fireworks, and matches. What is its name? 

– A.  potassium chlorite– B.  potassium chloride– C.  potassium(I) chlorite– D.  potassium(I) chlorate– E.  potassium chlorate

Problem

• The compound, (NH4)2S, can be used in analysis for trace amounts of metals present in a sample. What is its name? 

– A.  ammonium sulfide– B.  diammonium sulfide– C.  ammonium sulfite– D.  ammonia(I) sulfite– E.  ammonium(I) sulfide

Problem

• The substance, CaSe, is used in materials which are electron emitters. What is its name? 

– A.  calcium monoselenide– B.  calcium(II) selenide– C.  calcium selenide– D.  calcium(I) selenide– E.  calcium(II) selenium

Formulas of Ionic Compounds

• Chemical compounds must posses NO charge

• Formulas– Determine ions involved– Determine charge on each ion– Cross and drop the magnitude

• If the magnitude dropped beside a polyatomic is greater than 1, place the polyatomic ion in parenthesis and magnitude dropped as subscript outside parenthesis

– Simplify if the subscripts are divisible by same #

Problem

• Sodium oxide combines violently with water. Which of the following gives the formula for sodium oxide? 

– A.  NaO– B.  Na1O1

– C.  Na2O1

– D.  Na2O– E.  Na2O2

Problem

• Barium fluoride is used in embalming and in glass manufacturing. Which of the following gives the formula for barium fluoride? 

– A.  BaF2

– B.  Ba1F2

– C.  BaF

– D.  BaF1

– E.  Ba2F

Problem

• Zinc acetate is used in preserving wood and in manufacturing glazes for porcelain. What is its formula? 

– A.  ZnAc2

– B.  ZnCH3COO– C.  Zn(CH3COO)2

– D.  Zn2CH3COO– E.  ZnCH3COCH3

Problem

• Barium sulfate is used in manufacturing photographic paper. What is its formula? 

– A.  BaSO4

– B.  Ba(SO4)2

– C.  Ba2SO4

– D.  Ba2(SO4)3

– E.  BaSO3

Problem

• What is the formula for lead (II) oxide? 

– A.  PbO

– B.  PbO2

– C.  Pb2O

– D.  PbO4

– E.  Pb2O3

H+ and OH- Ions: An Introduction to Acids and Bases

• The importance of the H+ cation and the OH- anion is that they are fundamental to the concepts of acids and bases.

• Acid: A substance that provides H+ ions in water; for example, HCl H+ + Cl-

• Base: A substance that provides OH- ions in water; for example, NaOH Na+ + OH-

Optional Homework

• Text – 4.31, 4.32, 4.33, 4.38, 4.46, 4.48, 4.50, 4.52, 4.54, 4.56, 4.60, 4.62, 4.64, 4.66, 4.68, 4.70, 4.72, 4.74, 4.76, 4.90, 4.92, 4.96, 4.98

• Chapter 2 Homework – from website

Required Homework

• Assignment 4