John C. Kotz Paul M. Treichel John Townsend http://academic.cengage.com/kotz Chapter 1 Matter and Measurement John C. Kotz • State University of New York, College at Oneonta Important – Read Before Using Slides in Class Instructor: This PowerPoint presentation contains photos and figures from the text, as well as selected animations and videos. For animations and videos to run properly, we recommend that you run this PowerPoint presentation from the PowerLecture disc inserted in your computer. Also, for the mathematical symbols to display properly, you must install the supplied font called “Symb_chm,” supplied as a cross-platform TrueType font in the “Font_for_Lectures” folder in the "Media" folder on this disc. If you prefer to customize the presentation or run it without the PowerLecture disc inserted, the animations and videos will only run properly if you also copy the associated animation and video files for each chapter onto your computer. Follow these steps: 1. Go to the disc drive directory containing the PowerLecture disc, and then to the “Media” folder, and then to the “PowerPoint_Lectures” folder. 2. In the “PowerPoint_Lectures” folder, copy the entire chapter folder to your computer. Chapter folders are named “chapter1”, “chapter2”, etc. Each chapter folder contains the PowerPoint Lecture file as well as the animation and video files. For assistance with installing the fonts or copying the animations and video files, please visit our Technical Support at http://academic.cengage.com/support or call (800) 423-0563. Thank you. Welcome to the World of Chemistry PLAY MOVIE © 2009 Brooks/Cole - Cengage 3 The Language of Chemistry • CHEMICAL ELEMENTS - – pure substances that cannot be decomposed by ordinary means to other substances. Aluminum Sodium © 2009 Brooks/Cole - Cengage Bromine 4 5 Aluminum + Bromine PLAY MOVIE © 2009 Brooks/Cole - Cengage 6 The Language of Chemistry • The elements, their names, and symbols are given on the PERIODIC TABLE • How many elements are there? • 117 elements © 2009 Brooks/Cole - Cengage The Periodic Table Dmitri Mendeleev (1834 - 1907) © 2009 Brooks/Cole - Cengage 7 8 Glenn Seaborg (1912-1999 ) • Discovered 8 new elements. • Only living person for whom an element was named. © 2009 Brooks/Cole - Cengage 9 • An atom is the smallest particle of an element that has the chemical properties of the element. Copper atoms on silica surface. See Chemistry Now Screen 1.4 Distance across = 1.8 nanometer (1.8 x 10-9 m) © 2009 Brooks/Cole - Cengage The Atom An atom consists of a • nucleus –(of protons and neutrons) • electrons in space about the nucleus. © 2009 Brooks/Cole - Cengage 10 CHEMICAL COMPOUNDS are composed of atoms and so can be decomposed to those atoms. The red compound is composed of • nickel (Ni) (silver) • carbon (C) (black) • hydrogen (H) (white) • oxygen (O) (red) • nitrogen (N) (blue) © 2009 Brooks/Cole - Cengage 11 A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound. Composition of molecules is given by a MOLECULAR FORMULA H2O C8H10N4O2 - caffeine PLAY MOVIE © 2009 Brooks/Cole - Cengage 12 13 Elements form Compounds © 2009 Brooks/Cole - Cengage The Nature of Matter Gold 14 Mercury PLAY MOVIE Chemists are interested in the nature of matter and how this is related to its atoms and molecules. © 2009 Brooks/Cole - Cengage 15 Graphite — layer structure of carbon atoms reflects physical properties. © 2009 Brooks/Cole - Cengage 16 Chemistry & Matter • We can explore the MACROSCOPIC world — what we can see — • to understand the PARTICULATE worlds we cannot see. • We write SYMBOLS to describe these worlds. © 2009 Brooks/Cole - Cengage 17 A Chemist’s View of Matter © 2009 Brooks/Cole - Cengage 18 A Chemist’s View of Water PLAY MOVIE Macroscopic H 2O (gas, liquid, solid) Symbolic Particulate © 2009 Brooks/Cole - Cengage 19 A Chemist’s View PLAY MOVIE Macroscopic Particulate © 2009 Brooks/Cole - Cengage 2 H2(g) + O2 (g) f 2 H2O(g) Symbolic Kinetic Nature of Matter Matter consists of atoms and molecules in motion. PLAY MOVIE © 2009 Brooks/Cole - Cengage 20 21 STATES OF MATTER © 2009 Brooks/Cole - Cengage 22 STATES OF MATTER • SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement. – Reasonably well understood. • LIQUIDS — have no fixed shape and may not fill a container completely. – Not well understood. • GASES — expand to fill their container. – Good theoretical understanding. © 2009 Brooks/Cole - Cengage 23 Physical Properties What are some physical properties? • color • melting and boiling point • odor © 2009 Brooks/Cole - Cengage Physical Changes Some physical changes would be • boiling of a liquid • melting of a solid • dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION. © 2009 Brooks/Cole - Cengage 24 DENSITY - an important and useful physical property Density = mass (g) 3 volume (cm ) Mercury Platinum Aluminum 13.6 g/cm3 © 2009 Brooks/Cole - Cengage 21.5 g/cm3 2.7 g/cm3 25 26 Relative Densities of the Elements © 2009 Brooks/Cole - Cengage 27 Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3). Density = mass (g) 3 volume (cm ) © 2009 Brooks/Cole - Cengage Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density. © 2009 Brooks/Cole - Cengage 28 29 SOLUTION 1. Get dimensions in common units. 1cm 0.95 mm = 0.095 cm 10 mm 2. Calculate volume in cubic centimeters. (9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm3 Note only 2 significant figures in the answer! 3. Calculate the density. 57.54 g 6.4 cm3 © 2009 Brooks/Cole - Cengage = 9.0 g/cm3 DENSITY • Density is an INTENSIVE property of matter. –does NOT depend on quantity of matter. –temperature • Contrast with EXTENSIVE –depends on quantity of matter. –mass and volume. © 2009 Brooks/Cole - Cengage Styrofoam 30 Brick 31 PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds? Solve the problem using DIMENSIONAL ANALYSIS. © 2009 Brooks/Cole - Cengage 32 PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg? First, note that 1 cm3 = 1 mL Strategy 1. Use density to calc. mass (g) from volume. 2. Convert mass (g) to mass (lb) Need to know conversion factor = 454 g / 1 lb © 2009 Brooks/Cole - Cengage 33 PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg? 1. Convert volume to mass ( 95 cm3 )(13.6 g/cm3) = 1.3 x 103 g 2. Convert mass (g) to mass (lb) 1 lb 1.3 x 10 g = 2.8 lb 454 g 3 © 2009 Brooks/Cole - Cengage Chemical Properties and Chemical Change 34 • Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules. © 2009 Brooks/Cole - Cengage Types of Observations and Measurements • We make QUALITATIVE observations of reactions — changes in color and physical state. • We also make QUANTITATIVE MEASUREMENTS, which involve numbers. • Use SI units — based on the metric system © 2009 Brooks/Cole - Cengage 35 36 UNITS OF MEASUREMENT Use SI units — based on the metric system Length Meter, m Mass Kilogram, kg Time Seconds, s Temperature Celsius degrees, ˚C kelvins, K © 2009 Brooks/Cole - Cengage Units of Length • 1 kilometer (km) = ? meters (m) • 1 meter (m) = ? centimeters (cm) • 1 centimeter (cm) = ? millimeter (mm) • 1 nanometer (nm) = 1.0 x 10-9 meter O—H distance = 9.58 x 10-11 m 9.58 x 10-9 cm 0.0958 nm © 2009 Brooks/Cole - Cengage 37 Temperature Scales • Fahrenheit • Celsius • Kelvin Anders Celsius 1701-1744 Lord Kelvin (William Thomson) 1824-1907 © 2009 Brooks/Cole - Cengage 38 39 Temperature Scales Boiling point of water Freezing point of water Fahrenheit Celsius Kelvin 212 ˚F 100 ˚C 373 K 180˚F 100˚C 32 ˚F 0 ˚C 100 K 273 K Notice that 1 kelvin degree = 1 degree Celsius © 2009 Brooks/Cole - Cengage 40 Temperature Scales 100 oF 38 oC 311 K oF © 2009 Brooks/Cole - Cengage oC K 41 Calculations Using Temperature Generally require temp’s in kelvins T (K) = t (˚C) + 273.15 Body temp = 37 ˚C + 273 = 310 K Liquid nitrogen = -196 ˚C + 273 = 77 K © 2009 Brooks/Cole - Cengage