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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
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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
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-
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
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 acidsand 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