1 © 2006 Brooks/Cole - Thomson Kull Spring 2007 Chem 105 Lsn 4 Review: Density The density of...

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© 2006 Brooks/Cole - Thomson

Kull Spring 2007 Chem 105 Lsn 4

Review: Density

• The density of silver is 10.5 g/cm3. What is the volume of a piece of Ag that contains 2.8 × 1022 atoms?

• a. 0.48 cm3

• b. 53 cm3

• c. 4.8 × 10-2 cm3

• d. 2.1 cm3

• What is the length of 1 side?

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Chemistry and Chemical Reactivity 6th Edition

John C. Kotz Paul M. Treichel

Gabriela C. Weaver

CHAPTER 3

Molecules, Ions and Their Compounds

© 2006 Brooks/Cole Thomson

Lectures written by John Kotz

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3.1 Molecules, Compounds, & Formulas

•COMPOUNDSCOMPOUNDS are a combination of 2 are a combination of 2

or more elements in definite ratios by mass. or more elements in definite ratios by mass.

• The character of each element is lost when The character of each element is lost when

forming a compound.forming a compound.

•MOLECULESMOLECULES are the smallest unit of a are the smallest unit of a

compound that retains the characteristics of compound that retains the characteristics of

the compound.the compound.

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3.2 FORMULAS and 3.2 FORMULAS and 3.3 Molecular Models3.3 Molecular Models3.2 FORMULAS and 3.2 FORMULAS and

3.3 Molecular Models3.3 Molecular ModelsGlycine Glycine

• Molecular Formula: Molecular Formula: CC22HH55NONO22• Condensed Formula Condensed Formula

H2NCH2COOH to show atom ordering

• structuralstructural formula formula

C

H

H C

H

H

O

O HN

Ball & stickBall & stick Space-fillingSpace-filling

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3.3 Ionic compounds: Formulas, names, and Properties

• Ionic charges (use periodic table)– Desire for noble gas configuration– Cations (+)– Anions (-)

• 3.6 What charges are most commonly observed for monatomic ions of the following elements?(a)Selenium (b) fluorine(c) Iron (d) nitrogen

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Charges on Common Charges on Common IonsIons

Charges on Common Charges on Common IonsIons

+3

-4 -1-2-3+1

+2

By losing or gaining e-, atom has same By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.number of e-’s as nearest Group 8A atom.

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IONIC COMPOUNDSIONIC COMPOUNDSIONIC COMPOUNDSIONIC COMPOUNDS

NH4+

Cl-

ammonium chloride, NHammonium chloride, NH44ClCl

Name Name derived by derived by adding -ide adding -ide to stemto stem

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Note: many O containing anions have names ending in –ate (or -ite).

Note: many O containing anions have names ending in –ate (or -ite).

Table 3.1, page 107.Table 3.1, page 107.

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Some Ionic CompoundsSome Ionic CompoundsSome Ionic CompoundsSome Ionic Compounds

MgMg2+2+ + NO + NO33-- ----> ---->

Mg(NOMg(NO33))22

magnesiummagnesium nitratenitrate

FeFe2+2+ + PO + PO443-3- ----> ---->

FeFe33(PO(PO44))22

iron(II) phosphateiron(II) phosphate

(See CD, Screen 3.11 for naming practice)(See CD, Screen 3.11 for naming practice)

calcium fluoridecalcium fluoride

CaCa2+2+ + 2 F + 2 F-- ---> ---> CaFCaF22

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Properties of Ionic Properties of Ionic CompoundsCompounds

Forming NaCl from Na and ClForming NaCl from Na and Cl22

Properties of Ionic Properties of Ionic CompoundsCompounds

Forming NaCl from Na and ClForming NaCl from Na and Cl22

• A metal atom can A metal atom can transfer an electron to transfer an electron to a nonmetal.a nonmetal.

• The resulting cation The resulting cation and anion are and anion are attracted to each attracted to each other by other by

electrostatic electrostatic forcesforces..

• These forces are governed by These forces are governed by COULOMB’S LAWCOULOMB’S LAW..

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Electrostatic ForcesElectrostatic ForcesCOULOMB’S LAWCOULOMB’S LAW

Active Figure 3.10

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Importance of Coulomb’s Importance of Coulomb’s LawLaw

NaCl, NaNaCl, Na++ and Cl and Cl--,,m.p. 804 m.p. 804 ooCC

MgO, MgMgO, Mg2+2+ and O and O2-2-

m.p. 2800 m.p. 2800 ooCC

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NONMETALSNONMETALSNONMETALSNONMETALS

NONMETAL + n e- ------> XNONMETAL + n e- ------> Xn-n-

where n = 8 - Group no.where n = 8 - Group no.

CC4-4-,carbide,carbide NN3-3-, nitride, nitride OO2-2-, oxide, oxide

SS2-2-, sulfide, sulfide

FF--, fluoride, fluoride

ClCl--, chloride, chloride

Group 7AGroup 6AGroup 4A Group 5A

BrBr--, bromide, bromide

II--, iodide, iodide

Name Name derived by derived by adding -ide adding -ide to stemto stem

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3-14 For each of the following compounds, give the formula,

charge, and the number of each ion that makes up the compound.

(a)K2S

(b)CoSO4

(c)CuCO3

(d)Ti(SO4)2

(e)KH2PO4

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3-16 Platinum is a transition element and forms Pt2+ and Pt4+ ions. Write the formulas for the

compounds of each of these ions with (a) chloride ions and (b) sulfide

ions.

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CH4 methaneBCl3 boron trichloride

CO2 Carbon dioxide

All are formed from two or more nonmetals.

Ionic compounds generally involve a metal and nonmetal (NaCl)

3.4 Molecular 3.4 Molecular CompoundsCompounds

Compounds without IonsCompounds without Ions

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ELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS MOLECULESMOLECULES

ELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS MOLECULESMOLECULES

Allotropes of CAllotropes of CAllotropes of CAllotropes of C

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ELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS DIATOMICDIATOMIC MOLECULES MOLECULES

ELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS DIATOMICDIATOMIC MOLECULES MOLECULES

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ELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS POLYATOMICPOLYATOMIC MOLECULES MOLECULESELEMENTS THAT EXIST AS ELEMENTS THAT EXIST AS POLYATOMICPOLYATOMIC MOLECULES MOLECULES

White P4 and polymeric red phosphorus

S8 sulfur molecules

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3.5 Formulas, Compounds, and the mole grams/moles/somethings

a) Molar mass of C2H6O = 46.08 g/mol

(b) Calc. moles of alcohol

How many How many molesmoles of alcohol are of alcohol are there in a “standard” can of beer there in a “standard” can of beer if there are 21.3 g of Cif there are 21.3 g of C22HH66O?O?

How many How many moleculesmolecules of of alcohol are there in a “standard” can of alcohol are there in a “standard” can of beer if there are 21.3 g of Cbeer if there are 21.3 g of C22HH66O?O?

= 2.78 x 1023 molecules

0.462 mol • 6.022 x 1023 molecules

1 mol

21.3 g • 1 mol

46.08 g = 0.462 mol

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How many How many atoms of Catoms of C are there are there in a “standard” can of beer if there in a “standard” can of beer if there are 21.3 g of Care 21.3 g of C22HH66O?O?

= 5.57 x 1023 C atoms

There are 2.78 x 1023 molecules.

Each molecule contains 2 C atoms.

Therefore, the number of C atoms is

2.78 x 1023 molecules • 2 C atoms1 molecule

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3-22 Give the formula for each of the following ionic compounds.

(a) Calcium hydrogen carbonate

(b) Potassium permanganate

(c) Magnesium perchlorate

(d) Potassium hydrogen phosphate

(e) Sodium sulfite

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3-34 Calculate the molar mass of each hydrated compound. Note

that the water of hydration is included in the molar mass.

(a) H2C2O4 2 H2O

(b) MgSO4 7 H2O

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3-36 Assume you have 0.123 mol of each of the following compounds.

What mass of each is present?

(a) C14H10O4, benzoyl peroxide

(b) Pt(NH3)2Cl2, cisplatin

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3-66 The compound (NH4)2SO4 consists of two polyatomic ions. What are the names and electric

charges of these ions? What is the molar mass of this compound?

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68

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