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GENERAL CHEMISTRY Chapter 1: Matter—Its Properties and Measurement
Ninth Edition GENERAL Principles and Modern Applications Petrucci • Harwood • Herring • Madura Chapter 1: Matter—Its Properties and Measurement Philip Dutton University of Windsor, Canada Prentice-Hall © 2007 General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Chemistry 140 Fall 2002 Contents 1-1 The Scientific Method 1-2 Properties of Matter 1-3 Classification of Matter 1-4 Measurement of Matter: SI (Metric) System 1-5 Density and Percent Composition: Their Use in Problem Solving 1-6 Uncertainties in Scientific Measurements 1-7 Significant Figures Focus On The Scientific Method at Work: Polywater General Chemistry: Chapter 1 Prentice-Hall © 2007
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1-1 The Scientific Method
Louis Pasteur ( ) Developer of Germ Theory Pasteurization Rabies Vaccination Called the greatest physician of all time by some. He was a chemist by training and profession. General Chemistry: Chapter 1 Prentice-Hall © 2007
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Figure 1-1 The Scientific Method Illustrated
General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
1-2 Properties of Matter Matter: Occupies space, has mass and inertia Composition: Parts or components ex. H2O, 11.19% H and 88.81% O Properties: Distinguishing features physical and chemical properties General Chemistry: Chapter 1 Prentice-Hall © 2007
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1-2 Classification of Matter
Matter is made of atoms. 114 elements. About 90% available from natural sources Compounds are comprised of two or more elements. Molecules are the smallest units of compounds. General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Separating Mixtures General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Separating Mixtures General Chemistry: Chapter 1 General Chemistry: Chapter 1 Prentice-Hall © 2007
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Decomposing Compounds
General Chemistry: Chapter 1 General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Chemistry 140 Fall 2002 States of Matter General Chemistry: Chapter 1 General Chemistry: Chapter 1 Prentice-Hall © 2007
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1-4 The Measurement of Matter
General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Slide 12 of 19 General Chemistry: Chapter 1 General Chemistry: Chapter 1 Prentice-Hall © 2007 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Mass Mass is the quantity of matter in an object. Weight is the force of gravity on an object W m W = g m General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Temperature General Chemistry: Chapter 1 Prentice-Hall © 2007 Slide 14 of 28 General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Volume General Chemistry: Chapter 1 Prentice-Hall © 2007
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SI and non-SI Units Compared
1 Imperial qt 1.136 L 1 US qt 0.936 L 1 L 1 kg 1 lb 1 in 1 cm General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Units S.I. Units Length meter, m Mass Kilogram, kg Time second, s Temperature Kelvin, K Quantity Mole, 1023 mol-1 Derived Quantities Force Newton, kg m s-2 Pressure Pascal, kg m-1 s-2 Energy Joule, kg m2 s-2 Other Common Units Length Angstrom, Å, 10-8 cm Volume Liter, L, 10-3 m3 Energy Calorie, cal, J Pressure 1 Atm = 102 kPa 1 Atm = 760 mm Hg General Chemistry: Chapter 1 Prentice-Hall © 2007
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1-5 Density and Percent Composition
= m/V m=Vd V=m/d g/mL Mass and volume are extensive properties Density is an intensive property General Chemistry: Chapter 1 Prentice-Hall © 2007
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Density in Conversion Pathways
What is the mass of a cube of osmium that is 1.25 inches on each side? Have volume, need density = 22.48g/cm3 General Chemistry: Chapter 1 Prentice-Hall © 2007
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EXAMPLE 1-2 V = m d m 1 Calculate the Volume needed
Relating Mass, Volume and Density The stainless steel in the solid cylindrical rod pictured below has a density of 7.75 g/cm3. If we want a 1.00 kg mass of this rod, how long a section must we cut off? V = m d = m 1 Calculate the Volume needed Calculate the Length V = hr2 h = V r2 General Chemistry: Chapter 1 Prentice-Hall © 2007
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EXAMPLE 1-2 Calculate the Volume needed Calculate the Length m 1 V = =
(1.00kg)(1000g/kg) 7.75 g 1 cm3 V = = 129 cm3 V Calculate the Length V = hr2 h = r2 h = V r2 129 cm3 = = 25.5 cm (3.1415){(0.5)(1.000 in)(2.54 cm/in)}2 General Chemistry: Chapter 1 Prentice-Hall © 2007
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Measuring Volume of an Irregular Object
General Chemistry: Chapter 1 Prentice-Hall © 2007
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1-6 Uncertainties in Scientific Measurements
Systematic errors. Thermometer constantly 2°C too low. Random errors Limitation in reading a scale. Precision Reproducibility of a measurement. Accuracy How close to the real value. General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Precision Reproducibility 0.1 g g Precision low high General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
1-7 Significant Figures General Chemistry: Chapter 1 Prentice-Hall © 2007
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General Chemistry: Chapter 1
Significant Figures The calculators show the effect of the change in a low precision number in a calculation 5.05 General Chemistry: Chapter 1 Prentice-Hall © 2007
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End of Chapter Questions
Instructors may provide lists of questions that reinforce topics they feel are particularly pertinent in the chapter. If no list is given students should attempt questions from each section of the chapter. Build from the easier questions where the topic is identified, to the more difficult integrative examples where the approach to the question must be identified. General Chemistry: Chapter 1 Prentice-Hall © 2007
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GENERAL CHEMISTRY Chapter 2: Atoms and the Atomic Theory
Chemistry 140 Fall 2002 Petrucci • Harwood • Herring • Madura GENERAL Ninth Edition CHEMISTRY Principles and Modern Applications Chapter 2: Atoms and the Atomic Theory Philip Dutton University of Windsor, Canada Prentice-Hall © 2007 General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Contents 2-1 Early Chemical Discoveries and the Atomic Theory 2-2 Electrons and Other Discoveries in Atomic Physics 2-3 The Nuclear Atom 2-4 Chemical Elements 2-5 Atomic Mass General Chemistry: Chapter 2 Prentice-Hall © 2007
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Contents 2-6 Introduction to the Periodic Table
2-7 The Concept of the Mole and the Avogadro Constant 2-8 Using the Mole Concept in Calculations Focus On Occurrence and Abundances of the Elements General Chemistry: Chapter 2 Prentice-Hall © 2007
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2-1 Early Discoveries and the Atomic Theory
Lavoisier 1774 Law of conservation of mass Proust 1799 Law of constant composition Dalton Atomic Theory General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Conservation of Mass General Chemistry: Chapter 2 Prentice-Hall © 2007
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Dalton’s Atomic Theory
Each element is composed of small particles called atoms. Atoms are neither created nor destroyed in chemical reactions. All atoms of a given element are identical. Compounds are formed when atoms of more than one element combine. General Chemistry: Chapter 2 Prentice-Hall © 2007
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Consequences of Dalton’s theory
Law of Definite Proportions: combinations of elements are in ratios of small whole numbers. In forming carbon monoxide, 1.33 g of oxygen combines with 1.0 g of carbon. In the formation of carbon dioxide g of oxygen combines with 1.0 g of carbon. General Chemistry: Chapter 2 Prentice-Hall © 2007
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2-2 Electrons and Other Discoveries in Atomic Physics
General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Cathode ray tube General Chemistry: Chapter 2 Prentice-Hall © 2007
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Properties of cathode rays
Electron m/e = 10-9 g coulomb-1 General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Charge on the electron From Robert Millikan showed ionized oil drops can be balanced against the pull of gravity by an electric field. The charge is an integral multiple of the electronic charge, e. General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Radioactivity Radioactivity is the spontaneous emission of radiation from a substance. X-rays and g-rays are high-energy light. a-particles are a stream of helium nuclei, He2+. b-particles are a stream of high speed electrons that originate in the nucleus. General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
2-3 The Nuclear Atom Geiger and Rutherford 1909 General Chemistry: Chapter 2 Prentice-Hall © 2007
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The a-particle experiment
Most of the mass and all of the positive charge is concentrated in a small region called the nucleus . There are as many electrons outside the nucleus as there are units of positive charge on the nucleus General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
The Nuclear Atom Rutherford protons 1919 James Chadwick neutrons 1932 General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Nuclear Structure Atomic Diameter cm Nuclear diameter cm 1 Å Particle Mass Electric Charge kg amu Coulombs (e) Electron – –1 Proton Neutron General Chemistry: Chapter 2 Prentice-Hall © 2007
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Scale of Atoms The heaviest atom has a mass of only 4.8 10-22 g
and a diameter of only 5 m. Useful units: 1 amu (atomic mass unit) = g 1 pm (picometer) = 1 m 1 Å (Angstrom) = 1 m = 100 pm = 1 10-8 cm Biggest atom is 240 amu and is 50 Å across. Typical C-C bond length 154 pm (1.54 Å) Molecular models are 1 Å /inch or about 0.4 Å /cm General Chemistry: Chapter 2 Prentice-Hall © 2007
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To represent a particular atom we use symbolism:
Chemistry 140 Fall 2002 2-4 Chemical Elements To represent a particular atom we use symbolism: Often do not specify Z when writing. For example 14C, C specifies Z = 12. Special names for some isotopes. For example hydrogen, deuterium, tritium. A= mass number Z = atomic number General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Isotopic Masses General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
2-5 Atomic Mass General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-6 Relating the Masses and Natural Abundances of Isotopes to the Atomic Mass of an Element. Bromine has two naturally occurring isotopes. One of them, bromine-79 was a mass of u and an abundance of 50.69%. What must be the mass and percent natural abundance of the other, bromine-81? What do we know: The sum of the percent natural abundances must be 100%. The average mass of bromine (read from the periodic table) is the weighted contribution of the percent abundance times the mass of each contributing isotope. Recall equation 2.3. General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-6 Strategy Identify the unknown abundance of bromine-81 by calculation. Use this value in the equation for the average mass of an element to solve for the mass of the unknown isotope. Recall equation 2.3. Solution Write the general equations 100% = 1 + 2 + Atomic mass = 1 m 2 m 3 m General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-6 Identify the knowns and unknowns in the specific equations Atomic mass = Br-79 mBr Br-81 mBr-81 Solve 100% = 79 + 81 81 = 100% - 79 Atomic mass - (Br-79 mBr-79) mBr-81 = Br-81 General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-6 Calculate mBr-81 = u - ( u) 0.4931 = u General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
The Periodic table Noble Gases Alkali Metals Main Group Alkaline Earths Halogens Transition Metals Lanthanides and Actinides General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
The Periodic Table Read atomic masses. Read the ions formed by main group elements. Read the electron configuration. Learn trends in physical and chemical properties. We will discuss these in detail in Chapter 9. General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
The Mole Physically counting atoms is impossible. We must be able to relate measured mass to numbers of atoms. buying nails by the pound or kilogram. using atoms by the gram General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Avogadro’s number The mole is an amount of substance that contains the same number of elementary entities as there are carbon-12 atoms in exactly 12 g of carbon-12. NA = 1023 mol-1 General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
The Mole General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
Molar Mass The molar mass, M, is the mass of one mole of a substance. M (g/mol 12C) = A (g/atom 12C) NA (atoms 12C /mol 12C) General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-9 Combining Several Factors in a Calculation—Molar Mass, the Avogadro Constant, Percent Abundance. Potassium-40 is one of the few naturally occurring radioactive isotopes of elements of low atomic number. Its percent natural abundance among K isotopes is 0.012%. How many 40K atoms do you ingest by drinking one cup of whole milk containing 1.65 mg of K/mL? Want atoms of 40K, need atoms of K, Want atoms of K, need moles of K, Want moles of K, need total mass of K and M(K) (the molar mass). General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-9 Convert concentration of K (mg/mL K) into mass of K (g K) cK(mg/mL) V (mL) mK (mg) (1g/1000mg) mK(g) nK = (1.65 mg/mL K) (225 mL) (1 g/1000 mg) = 0.37l g K Convert mass of K(g K) into moles of K (mol K) mK (g) 1/MK (mol/g) nK (mol) nK = (0.371 g K) (1 mol K) / (39.10 g K) = 9.49 10-3 mol K General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 2
EXAMPLE 2-9 Convert moles of K into atoms of 40K nK(mol) NA atoms K 0.012% atoms 40K atoms 40K = (9.49 10-3 mol K) (6.022 1023 atoms K/mol K) x (1.2 K/K) = 6.9 K atoms Note that the text shows two slightly different methods. There is often more than one correct way to solve a problem, but the strategy for the solution is often the same for any of the calculations. General Chemistry: Chapter 2 Prentice-Hall © 2007
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End of Chapter Questions
Problem solving is an integral part of the learning process. You must exercise your skills just like a varsity athlete does. Use your coaches, they can help you with skills for success. General Chemistry: Chapter 2 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Petrucci • Harwood • Herring • Madura GENERAL Ninth Edition CHEMISTRY Principles and Modern Applications Chapter 3: Chemical Compounds Philip Dutton University of Windsor, Canada Prentice-Hall © 2007 General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Contents 3-1 Types of Chemical Compounds and Their Formulas 3-2 The Mole Concept and Chemical Compounds 3-3 The Composition of Chemical Compounds 3-4 Oxidation States: A Useful Tool in Describing Chemical Compounds 3-5 Naming Compounds: Organic and Inorganic Compounds General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Contents 3-6 Names and Formulas of Inorganic Compounds 3-7 Names and Formulas of Organic Compounds Focus On Mass Spectrometry-Determining Molecular Formulas General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-1 Types of Chemical Compounds and Their Formulas
Molecular Compounds General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Molecular compounds 1 /inch 0.4 /cm Chemical formula – relative numbers of atoms of each element present Empirical formula – the simplest whole number formula Structural formula – the order and type of attachements – shows multiple bonds - may show lone pairs - hard to show 3-d General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Standard Color Scheme General Chemistry: Chapter 3 Prentice-Hall © 2007
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Some Organic and Inorganic Molecules
H2O2 CH3CH2Cl P4O10 CH3CH(OH)CH3 HCO2H General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Organic Compounds General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Ionic Compounds Atoms of almost all elements can gain or lose electrons to form charged species called ions. Compounds composed of ions are known as ionic compounds. Metals tend to lose electrons to form positively charged ions called cations. Non-metals tend to gain electrons to form negatively charged ions called anions. Positive and negaive ions joined together by electrostatic forces Metals tend to lose electrons to form cations Non-metals tend to gain electrons to form anions Ionic solids formulae are reported as the formula unit – inappropriate to call it a molecular formula General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Sodium Chloride An extended array of Na+ and Cl- ions The simplest formula unit is NaCl Na loses one electron to form the sodium ion Cl gains one electron to form the chloride ion Centers of ions are shown in the ball and stick model for clarity Space filling model shows how the ions are actually in contact with one another. We will discuss face centered cubic and other types of packing in chapter 13 General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-2 The Mole Concept and Chemical Calculations
Formula mass the mass of a formula unit in atomic mass units (u) Molecular mass a formula mass of a molecular compound Weighted average mass add up the weighted average atomic masses Exact Mass add up the isotopic masses (see mass spectrometry) General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
EXAMPLE 3-2 Combining Several Factors in a Calculation Involving Molar Mass. The volatile liquid ethyl mercaptan, C2H5SH is one of the most odoriferous substances known. It is sometimes added to natural gas to make gas leaks detectable. How many C2H5SH molecules are contained in a 1.0 L sample given the following information? The density is 0.84 g/mL, a drop of liquid is about 0.05 mL and 1.0 L is only 0.02 of a drop. General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
EXAMPLE 7-3 Solution. The strategy to follow can be laid out in a flow diagram. 1 mol 62.1 g 10-6 L/L 103 mL/L 0.84 g/mL molec/mol L L mL g mol molecules The factors in each conversion may be added above the arrows. Don’t worry if your conversion factors are upside down, fix them when you write the equations by making sure the units cancel properly. Using the strategy and the conversion factors, write the equation: 10-6 L/L 103 mL/L 0.84 g/mL 6.02 1023 molec/mol 1 mol 62.1 g 1 L Check the units cancel and only then calculate. = 8.1 1018 molecules General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Inorganic Molecules Some inorganic compounds for molecules Sulfur and phosporous for example. They come in various forms called allotropes – these are one allotrope of each General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Molecular Mass Glucose Molecular formula C6H12O6 Empirical formula CH2O 6 16.00 Molecular Mass: Use the naturally occurring mixture of isotopes, = Glucose Emprical formula leads us to the name “carbohydrate” Exact Mass: Use the most abundant isotopes, 6 = General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-3 Composition of Chemical Compounds
Chemistry 140 Fall 2002 3-3 Composition of Chemical Compounds Halothane C2HBrClF3 Mole ratio nC/nhalothane Mass ratio mC/mhalothane Molecular formula tells us there are TWO moles of C per mole of halothane. We also know about the MASSES of the compound and its elemental components. Therefore we can talk about PERCENT COMPOSITION BY MASS M(C2HBrClF3) = 2MC + MH + MBr + MCl + 3MF = (2 12.01) (3 19.00) = g/mol General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
EXAMPLE 7-3 Calculating the Mass Percent Composition of a Compound What is the mass percent composition of halothane, C2HBrClF3? Calculate the molecular mass M(C2HBrClF3) = g/mol For one mole of compound, formulate the mass ratio and convert to percent: %C = 2 mol C 12.01 g C 1 mol C g C2HBrClF3 100% = 12.17% General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 EXAMPLE 7-3 1.01 g H 1 mol H 1 mol H %H = 100% = 0.51% H g C2HBrClF3 79.90 g Br 1 mol Br 1 mol Br %Br = 100% = 40.48% Br g C2HBrClF3 35.45 g Cl 1 mol C 1 mol Cl %Cl = 100% = 17.96% Cl g C2HBrClF3 These types of calculations can be carried out in reverse for the following reasons: Unknown compounds are analyzed for % composition. Relative proportion of elements present on a mass basis. Chemical formula requires mole basis, I.e. numbers of atoms. 19.00 g F 3 mol C 1 mol F %F = 100% = 28.88% F g C2HBrClF3 General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Establishing Formulas from Experimentally Determined Percent Composition 5 Step approach: Choose an arbitrary sample size (100g). Convert masses to amounts in moles. Write a formula. Convert formula to small whole numbers. Multiply all subscripts by a small whole number to make the subscripts integral. If you know the molecular wt it is beneficial to choose that number, then only first three steps are required. General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 EXAMPLE 3-5 Determining the Empirical and Molecular Formulas of a Compound from Its Mass Percent Composition Dibutyl succinate is an insect repellent used against household ants and roaches. Its composition is 62.58% C, 9.63% H and 27.79% O. Its experimentally determined molecular mass is 230 u. What are the empirical and molecular formulas of dibutyl succinate? Step 1: Determine the mass of each element in a 100g sample. Read the problem carefully Pick out the critical information Think Follow the steps to solve the problem C g H 9.63 g O g General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
EXAMPLE 3-5 Step 2: Convert masses to amounts in moles. Step 3: Write a tentative formula. C5.21H9.55O1.74 Step 4: Convert to small whole numbers. C2.99H5.49O General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 EXAMPLE 3-5 Step 5: Convert to a small whole number ratio. Multiply 2 to get C5.98H10.98O2 The empirical formula is C6H11O2 Step 6: Determine the molecular formula. Empirical formula mass is 115 u. Molecular formula mass is 230 u. The molecular formula is C12H22O4 Step 5. You can multiply the rounded off one if you wish, but be careful of introducing an error If all the subscripts are within ±0.1 you are probably OK to round to the integer. Step 6: Simple multiplication is obvious here. General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Combustion Analysis Water vapour absorbed by magnesium perchlorate Carbon dioxide absorbed by sodium hydroxide. The differences in mass of the absorbers before and after yiled the masses of water and CO2 produced in the reaction Combustion takes place in an excess of oxygen so you cannot measure oxygen. Oxygen CAN be analyzed separately but is usually determined by difference. General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-4 Oxidation States: A Useful Tool in Describing Chemical Compounds
Chemistry 140 Fall 2002 3-4 Oxidation States: A Useful Tool in Describing Chemical Compounds Metals tend to lose electrons. Na Na+ + e- Non-metals tend to gain electrons. Cl + e- Cl- Reducing agents Oxidizing agents Metals are electron sources Non-metals are electron sinks Sodium goes to the +1 oxidation state Chlorine goes tot eh –1 oxidation state We use the Oxidation State to keep track of the number of electrons that have been gained or lost by an element. General Chemistry: Chapter 3 Prentice-Hall © 2007
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Rules for Oxidation States
The oxidation state (OS) of an individual atom in a free element is 0. The total of the OS in all atoms in: Neutral species is 0. Ionic species is equal to the charge on the ion. In their compounds, the alkali metals and the alkaline earths have OS of +1 and +2 respectively. In compounds the OS of fluorine is always –1 General Chemistry: Chapter 3 Prentice-Hall © 2007
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Rules for Oxidation States
In compounds, the OS of hydrogen is usually +1 In compounds, the OS of oxygen is usually –2. In binary (two-element) compounds with metals: Halogens have OS of –1, Group 16 have OS of –2 and Group 15 have OS of –3. General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 EXAMPLE 3-7 Assigning Oxidation States What is the oxidation state of the underlined element in each of the following? a) P4; b) Al2O3; c) MnO4-; d) NaH. P4 is an element. P OS = 0 Al2O3: O is –2. O3 is –6. Since (+6)/2=(+3), Al OS = +3. MnO4-: net OS = -1, O4 is –8. Mn OS = +7. NaH: net OS = 0, rule 3 beats rule 5, Na OS = +1 and H OS = -1. Rule 1 states OS of elements is 0 Rule 2 the total OS is 0, Rule 6 oxygen should be –2 to give a total of –6 for O, therefore 2 Al must be +6 or each Al is +3. Rule 2 the total OS is –1, Rule 6 oxygen should be –2 to give a total of –8 for O, therefore Mn must be +7. Rule 2 the total OS is –1, Rule 3 beats Rule 5, so Na OS = +1 and H OS = -1. There are other examples in the text and much more detail on the rules. Read this material carefully. General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-5 Naming Compounds: Organic and Inorganic Compounds
Chemistry 140 Fall 2002 3-5 Naming Compounds: Organic and Inorganic Compounds Trivial names are used for common compounds. A systematic method of naming compounds is known as a system of nomenclature. Organic compounds Inorganic compounds Trivial names such as water, ammonia, sugar, acetone, ether. Lead (IV) oxide Lead (II) oxide General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-6 Names and Formulas of Inorganic Compounds
Chemistry 140 Fall 2002 3-6 Names and Formulas of Inorganic Compounds Binary Compounds of Metals and Nonmetals Write the unmodified name of the metal Then write the name of the nonmetal, modifed to end in ide. Ionic compounds must be electrically neutral General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 We have already discussed simple anions such as hydride, fluoride, chloride, iodide etc. General Chemistry: Chapter 3 Prentice-Hall © 2007
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Binary Compounds of Two Non-Metals
Molecular compounds usually write the positive OS element first. HCl hydrogen chloride mono 1 penta 5 di 2 hexa 6 tri 3 hepta 7 tetra 4 octa 8 Some pairs form more than one compound General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Prentice-Hall © 2007
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General Chemistry: Chapter 3
Binary Acids Acids produce H+ when dissolved in water. They are compounds that ionize in water. Emphasize the fact that a molecule is an acid by altering the name. HCl hydrogen chloride hydrochloric acid HF hydrogen fluoride hydrofluoric acid General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Most oxoacids are ternary compounds composed of hydrogen, oxygen and one other nonmental. Oxoacids are molecular compounds, salts are ionic compounds Ic and ate names are assigned to compounds (rather than ite and ate as in the oxoanions) in which the central nonmetal atom has an oxidation state equal to the periodic group number – 10 For halogens ic and ate names are assigned to compounds in which the halogen has an oxidation state of +5. General Chemistry: Chapter 3 Prentice-Hall © 2007
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Some Compounds of Greater Complexity
Effect of Moisture Blue anhydrous CoCl2 Pink hexahydrate CoCl2• 6 H2O %H2O = 6 mol H2O 18.02 g H2O 1 mol H2O 237.9 g CoCl2• 6 H2O 100% = 45.45% H2O General Chemistry: Chapter 3 Prentice-Hall © 2007
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3-7 Names and Formulas of Organic Compounds
Organic compounds abound in nature Fats, carbohydrates and proteins are foods. Propane, gasoline, kerosene, oil. Drugs and plastics Carbon atoms form chains and rings and act as the framework of molecules. General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
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Visualizations of some Hydrocarbons
General Chemistry: Chapter 3 Prentice-Hall © 2007
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General Chemistry: Chapter 3
Chemistry 140 Fall 2002 Isomers Isomers have the same molecular formula but have different arrangements of atoms in space. Are the following pairs isomers? These are structural isomers. The structures are different these molecules do not have the same formula, they are different c) Now these molecules have the same formula and ALSO the same connectivity. These are geometric isomers. H (c) General Chemistry: Chapter 3 Prentice-Hall © 2007
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Functional Groups – Alcohols
General Chemistry: Chapter 3 Prentice-Hall © 2007
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Functional Groups – Carboxylic Acid
General Chemistry: Chapter 3 Prentice-Hall © 2007
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End of Chapter Questions
Individuals have individual learning styles. You may have more than one style for different types of learning. Take notes and actively listen. Participate in your learning process! Seeing Reading Listening Writing General Chemistry: Chapter 3 Prentice-Hall © 2007
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