Chemistry: Matter on the Atomic Scale - Young_MTx Atoms1st_CH01.pptx PDF

Chapter 1. Chemistry: Matter on the Atomic Scale 1.1 What Is Chemistry? 1.2 Classification of Matter 1.3 Units and Measurement 1.4 Unit Conversions This chapter introduces the fundamental components of matter, the different types of structures they can make when they join together, and t...

Chapter 1. Chemistry: Matter on the Atomic Scale 1.1 What Is Chemistry? 1.2 Classification of Matter 1.3 Units and Measurement 1.4 Unit Conversions This chapter introduces the fundamental components of matter, the different types of structures they can make when they join together, and the types of changes they undergo. © 2018 Cengage Learning. All Rights Reserved.  Chemistry: Matter on the Atomic Scale 1.1 What Is Chemistry? © 2018 Cengage Learning. All Rights Reserved. 2  What Is Chemistry? Study of matter – Transformations of matter – Behavior of matter Matter: – Occupies space – Has mass – Consists of atoms and molecules Chemical transformations take place in atomic and molecular levels © 2018 Cengage Learning. All Rights Reserved. 3  The Scale of Chemistry Macroscopic – Matter that can be seen with the naked eye Atomic Piece of native Cu – Nanoscale or molecular scale – Individual atoms and molecules cannot be seen STM image of copper atoms on a silica surface © 2018 Cengage Learning. All Rights Reserved. 4  Interactive Figure 1.1.1 - Understand the Scale of Science The macroscopic, microscopic, and atomic scales in different fields of science © 2018 Cengage Learning. All Rights Reserved. 5  Chemistry as an Experimental Science Purpose of chemistry – To design thoughtful experiments – To make careful observations of macroscopic amounts of matter Careful observations are required All ideas are open to challenge Scientific method: Examining results to see if there are alternative ways to interpret the data © 2018 Cengage Learning. All Rights Reserved. 6  Qualitative Observations Color, appearance, and statements, such as large or small Stating something as hot or cold without specifying a temperature Identifying something by smell No measurements or numbers are involved © 2018 Cengage Learning. All Rights Reserved. 7  Quantitative Observations Quantity or attribute that is measurable Numbers are expressed along with the units Dimensions such as mass, time, distance, volume, density, temperature, and color © 2018 Cengage Learning. All Rights Reserved. 8  Quantitative and Qualitative Observations Quantitative observations – Weighing out 6.25 grams of NaCl – Observing the wavelength of light to be 681 nm – Measuring the temperature of an object to be 27 C Can you change the above to qualitative observations? – _________________________________ – _________________________________ – _________________________________ © 2018 Cengage Learning. All Rights Reserved. 9  Example Problem 1.1.1 - Differentiate between the Macroscopic and Atomic Scales © 2018 Cengage Learning. All Rights Reserved. 10  Chemistry: Matter on the Atomic Scale 1.2 Classification of Matter © 2018 Cengage Learning. All Rights Reserved. 11  Elements Simplest type of matter Pure substances that cannot be broken down further Total recorded on the periodic table - 118 Common elements and symbols © 2018 Cengage Learning. All Rights Reserved. 12  Atom, Compound, and Molecule Atom: Smallest indivisible unit of an element Chemical compound: Substance formed when two or more elements are combined in a defined ratio Molecule: Collection of atoms held together by chemical bonds © 2018 Cengage Learning. All Rights Reserved. 13  Pure Substances Contain only one type of element or compound Have a fixed chemical composition Have well-defined physical and chemical properties – Physical properties: Do not change the chemical composition of the material when they are measured Physical state, color, viscosity (resistance to flow), opacity, density, conductivity, and melting and boiling points © 2018 Cengage Learning. All Rights Reserved. 14 Example Problem 1.2.1 - Classify Pure Substances as Elements or Compounds © 2018 Cengage Learning. All Rights Reserved. 15  States of Matter Matter can be classified as solid, liquid, and gas State Shape Volume Compress Flow Solid Fixed Fixed No No Liquid Indefinite Fixed No Yes Gas Indefinite Indefinite Yes Yes Fixed = Keeps shape when placed in a container Indefinite = Takes the shape of the container © 2018 Cengage Learning. All Rights Reserved. 16  States of Matter (continued 1) Solids: Have a definite shape – Particles are closely packed together Do not move past one another Vibrate back and forth about their average positions Liquids: Flow and take on the shape of the container – Particles are not confined to specific locations Can move past one another © 2018 Cengage Learning. All Rights Reserved. 17  States of Matter (continued 2) Gases – No fixed shape or volume – Particles are spaced widely apart and move rapidly past one another Move freely until they collide with one another or with the walls of the container © 2018 Cengage Learning. All Rights Reserved. 18  Physical Change Change in the physical property of a substance – May affect appearance and physical state but not the chemical composition Melting point: Temperature at which a solid is converted to a liquid when energy is added Freezing point: Temperature at which a liquid is converted to a solid when energy is removed Boiling point: Temperature at which a liquid is converted to a gas © 2018 Cengage Learning. All Rights Reserved. 19  Identify Intensive Properties Physical property Using the property Color What is the color of the substance? State of matter Is the substance a solid, liquid, or a gas? Melting point At what temperature does it melt? Boiling point At what temperature does it boil? Density What is the mass/volume relationship of the substance? Solubility What does the substance dissolve in? How much of the substance will dissolve at a given temperature? Viscosity How does the substance flow? Ductility Can you pull the substance into a wire? Conductivity Does the substance have electrical conductivity? Malleability Can you form the substance into sheets or other forms? © 2018 Cengage Learning. All Rights Reserved. 20  Chemical Properties Involve: – Chemical change in a material – Substances interacting with other chemicals Chemical change: Change in the chemical composition of the material Example - Flammability – Methanol is highly flammable because it reacts with oxygen in the air © 2018 Cengage Learning. All Rights Reserved. 21  What Is a Chemical Equation? Burning of ammonium dichromate (NH 4 )2 Cr2 O7 s  N 2  g  + 4 H 2 O  g  + Cr2O3 s  Copper placed in nitric acid Cu s  + 4 HNO3 aq  Cu(NO3 )2 aq  + 2 NO2 g  + 2 H 2O l  Sucrose reacting with sulfuric acid C12 H 22 O11 s  + 11 H 2SO4 conc  12 C s  + 11 H 2SO4 + H 2O l  © 2018 Cengage Learning. All Rights Reserved. 22 Example Problem 1.2.2 - Identify Physical and Chemical Properties and Physical and Chemical Changes © 2018 Cengage Learning. All Rights Reserved. 23  Mixture Substance made up of Types two or more elements or – Homogeneous compounds that have – Heterogeneous not reacted chemically Has physical and Not a pure substance chemical properties that – Can be separated by depend on the physical means into two composition of the or more pure substances mixture © 2018 Cengage Learning. All Rights Reserved. 24  Mixture (continued) Homogeneous Heterogeneous Constant composition No uniform composition throughout the material © 2018 Cengage Learning. All Rights Reserved. 25  Separating Mixtures Mixtures may be separated on the basis of physical properties Physical property Means of separation Density Decantation and centrifugation Boiling point Distillation State of matter Filtration Intermolecular forces Chromatography Vapor pressure Evaporation Magnetism Magnets Solubility Filtration © 2018 Cengage Learning. All Rights Reserved. 26 Interactive Figure 1.2.6 - Classify Matter A flow chart for the classification of matter © 2018 Cengage Learning. All Rights Reserved. 27 Example Problem 1.2.3 - Identify Pure Substances and Mixtures © 2018 Cengage Learning. All Rights Reserved. 28  Chemistry: Matter on the Atomic Scale 1.3 Units and Measurement © 2018 Cengage Learning. All Rights Reserved. 29  Note about Math and Chemistry Numbers and mathematics are an inherent and unavoidable part of general chemistry Students must possess secondary algebra skills and the ability to recognize orders of magnitude quickly with respect to numerical information to assure success in this course Material presented in this chapter is considered to be a prerequisite to this course © 2018 Cengage Learning. All Rights Reserved. 30  Units and Measurement Careful measurements help infer the properties of matter on the atomic scale – Common measurements in chemistry are mass, volume, time, temperature, and density Scientific units are used to report measurement – SI units (Système International d’Unités) Combined with metric prefixes for reflecting the relative size of the measured quantity © 2018 Cengage Learning. All Rights Reserved. 31 Table 1.3.1 - SI Units © 2018 Cengage Learning. All Rights Reserved. 32 Table 1.3.2 - Common Prefixes Used in the SI and Metric Systems © 2018 Cengage Learning. All Rights Reserved. 33  Scientific Notation Used to represent very large or very small numbers General form is N × 10x – N is a number between 1 and 10 – x is a positive or negative integer © 2018 Cengage Learning. All Rights Reserved. 34  Scientific Notation (continued 1) Converting standard notation to scientific notation – Count the number of times the decimal point is moved to the right or left to result in a number between 1 and 10 13433.0 = 1.3433  10 4 -3 0.0058 = 5.8  10 © 2018 Cengage Learning. All Rights Reserved. 35  Scientific Notation (continued 2) The terminology 4 1.23  10 Coefficient or mantissa Base Exponent (This number is 1 and