Chemistry: The Central Science Lecture Notes PDF

Chemistry: The Central Science Fifteenth Edition Chapter 1 Introduction: Matter, Energy, and Measurement Copyright © 2023 Pearson Education, Inc. All Rights Re...

Chemistry: The Central Science Fifteenth Edition Chapter 1 Introduction: Matter, Energy, and Measurement Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.1 Chemistry Chemistry is the study of matter, its properties, and the changes it undergoes. It is central to our fundamental understanding of many science-related fields. Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.2 Classifications of Matter Matter is anything that has mass and takes up space. States of matter Composition of matter Examples Copyright © 2023 Pearson Education, Inc. All Rights Reserved States of Matter The three states of matter are 1) solid. 2) liquid. 3) gas. In this figure, those states are ice, liquid water, and water vapor. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Classification of Matter as Substances A substance has distinct properties and a composition that does not vary from sample to sample. The two types of substances are elements and compounds. – An element is a substance which can not be decomposed to simpler substances. – A compound is a substance which can be decomposed to simpler substances because it is made up of more than one element. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Classification of Matter Based on Composition Atoms are the building blocks of matter. Each element is made of a unique kind of atom, but can be made of more than one atom of that kind. A compound is made of atoms from two or more Note: Balls of different colors are used to represent atoms different elements. of different elements. Attached balls represent connections between atoms that are seen in nature. These groups of atoms are called molecules. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Representing Elements Table 1.1 Some Common Elements and Their Symbols Carbon C Aluminum Al Copper Cu (from cuprum) Fluorine F Bromine Br Iron Fe (from ferrum) Hydrogen H Calcium Ca Lead Pb (from plumbum) Iodine I Chlorine Cl Mercury Hg (from hydrargyrum) Nitrogen N Helium He Potassium K (from kalium) Oxygen O Lithium Li Silver Ag (from argentum) Phosphorus P Magnesium Mg Sodium Na (from natrium) Sulfur S Silicon Si Tin Sn (from stannum) Chemists usually represent elements as symbols. Symbols are one or two letters; the first is always capitalized. Some elements are based on Latin, Greek, or other foreign language names. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Elements and Composition There are currently 118 named elements. Only five elements make up 90% of the Earth’s crust by mass. Only three elements make up 90% of the human body by mass. Note the importance of oxygen. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Compounds and Composition Compounds have a definite composition. That means that the relative number of atoms of each element in the compound is the same in any sample. This is the Law of Constant Composition (or the Law of Definite Proportions). Copyright © 2023 Pearson Education, Inc. All Rights Reserved Mixtures Mixtures exhibit the properties of the substances that make them. Mixtures can vary in composition throughout a sample (heterogeneous) or can have the same composition throughout the sample (homogeneous). A homogeneous mixture is also called a solution. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Making a Decision If you follow this scheme, you can determine how to classify any type of matter: – Homogeneous mixture – Heterogeneous mixture – Element – Compound Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.3 Properties of Matter Types of properties Major distinction – Physical properties – Chemical properties Further distinction – Intensive properties – Extensive properties Copyright © 2023 Pearson Education, Inc. All Rights Reserved Physical Properties Physical properties can be observed without changing a substance into another substance. – Some examples include color, odor, density, melting point, boiling point, and hardness. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Chemical Properties Chemical properties can only be observed when a substance is changed into another substance. – One common chemical property is flammability, or the ability to burn in oxygen. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Property Type—Further Distinction Intensive properties are independent of the amount of the substance that is present. – Examples include density, boiling point, or color. – These are important for identifying a substance. Extensive properties depend upon the amount of the substance present. – Examples include mass, volume, or energy. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Physical and Chemical Changes Physical changes are changes in matter that do not change the composition of a substance. – Examples include changes of state, temperature, and volume. Chemical changes result in new substances. – Examples include combustion, oxidation, and decomposition. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Physical Change Converting between the three states of matter is a physical change. When ice melts or water evaporates, there are still 2 H atoms and 1 O atom in each molecule. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Chemical Change (Chemical Reactions) In the course of a chemical reaction, the reacting substances are converted to new substances. Here, the copper penny reacts with nitric acid; it gives a blue solution of copper(II) nitrate and a brown gas called nitrogen dioxide. Note: Physical properties, like color, often helps us see that chemical change has occurred. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Separating Mixtures Mixtures can be separated based on physical properties of the components of the mixture. Some methods used are: – filtration – distillation – chromatography Copyright © 2023 Pearson Education, Inc. All Rights Reserved Filtration In filtration, solid substances are separated from liquids and solutions. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Distillation Distillation uses differences in the boiling points of substances to separate a liquid homogeneous mixture into its components. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Chromatography This technique separates substances on the basis of differences in the ability of substances to adhere to the solid surface, in this case, a liquid homogeneous mixture to a porous solid. Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.4 Energy Energy is the capacity to do work or transfer heat. Work is the energy transferred when a force exerted on an object causes a displacement of that object. Heat is the energy used to cause the temperature of an object to increase. Force is any push or pull on an object. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Two Fundamental Forms of Energy Kinetic energy is the energy of motion. – Its magnitude depends on the object’s mass and its velocity: 1 KE  mv 2 2 Potential energy of an object depends on its relative position compared to other objects. It is stored energy. Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.5 Units of Measurement Numbers play a major role in chemistry. Many topics are quantitative (have a numerical value). Concepts of numbers in science – Units of measurement – Quantities that are measured and calculated – Uncertainty in measurement – Significant figures – Dimensional analysis Copyright © 2023 Pearson Education, Inc. All Rights Reserved Units of Measurements—SI Units Système International d’Unités (“The International System of Units”) A different base unit is used for each quantity. Table 1.3 SI Base Units Physical Quantity Name of Unit Abbreviation Length Meter m Mass Kilogram kg Temperature Kelvin K Time Second s or sec Amount of substance Mole Mol Electric current Ampere A or amp Luminous intensity Candela cd Copyright © 2023 Pearson Education, Inc. All Rights Reserved Units of Measurement—Metric System The base units used in the metric system – Mass: gram (g) – Length: meter (m) – Time: second (s or sec) – Temperature: degrees Celsius(°C) or Kelvins (K) – Amount of a substance: mole (mol) – Volume: cubic centimeter (cc or cm3 ) or liter (l) Prefixes convert the base units into units that are appropriate for common usage or appropriate measure (liter on the soda bottle). Copyright © 2023 Pearson Education, Inc. All Rights Reserved Units of Measurement—Metric System Prefixes (1 of 2) Table 1.4 Prefixes Used in the Metric System and with SI Units Prefix Abbreviation Meaning Example Peta P = 11015 watts a 1015 10 to the fifteenth power 1 petawatt (PW) 1 petawatt, P W = 1 times 10 to the fifteenth power watts superscript a Tera T = 11012 watts 1012 10 to the twelfth power 1 terawatt (TW) 1 terawatt, T W = 1 times 10 to the twelfth power watts Giga G 1 gigawatt (GW) = 1109 watts 109 10 to the ninth power 1 gigawatt, G W = 1 times 10 to the ninth power watts Mega M = 110 6 watts 106 10 to the sixth power 1 megawatt (MW) 1 megawatt, M W = 1 times 10 to the sixth power watts Kilo k = 1103 watts 103 10 cubed 1 kilowatt (kW) 1 kilowatt, k W = 1 times 10 cubed watts Deci d 10 1 10 to the negative first power 1 deciwatt (dW) 1 deciwatt, d W = 1 times 10 to the negative first power watt = 110  1 watt Centi c 10 2 10 to the negative second power 1 centiwatt (cW) 1 centiwatt, c W = 1 times 10 to the negative second power watt = 110  2 watt Milli m 1 milliwatt (mW) 110  3 watt 10 3 10 to the negative third power 1 milliwatt, m W = 1 times 10 to the negative third power watt Micro 1 microwatt (  W) 110  6 watt b Mu super b 10 6 10 to the negative sixth power 1 microwatt, mu W = 1 times 10 to the negative sixth power watt Copyright © 2023 Pearson Education, Inc. All Rights Reserved Units of Measurement—Metric System Prefixes (2 of 2) Table 1.4 [continued] Prefix Abbreviation Meaning Example Nano n 1 nanowatt (nW) 110  9 watt 10 9 10 to the negative ninth power 1 nanowatt, n W = 1 times 10 to the negative ninth power watt Pico p 10 12 10 to the negative twelfth power 1 picowatt (pW) 1 picowatt, p W = 1 times 10 to the negative twelfth power watt 110  12 watt Femto f 10  15 10 to the negative fifteenth power 1 femtowatt (fW) 110  15 watt 1 femtowatt, f W = 1 times 10 to the negative fifteenth power watt Atto a 1 attowatt (aW) 110  18 watt 10  18 10 to the negative eighteenth power 1 attowatt, a W = 1 times 10 to the negative eighteenth power watt Zepto z 1 zeptowatt (zW) 110  21 watt 10  21 10 to the negative 20 first power 1 zeptowatt, z W = 1 times negative 20 first power watt a The watt (W) is the S I unit of power, which is the rate at which energy is either generated or consumed. The SI unit of energy is the joule (J); 1 J 1 kg m2 /s2 and 1 W 1 J/s. b Greek letter mu, pronounced “mew.” Copyright © 2023 Pearson Education, Inc. All Rights Reserved Mass and Length Units Mass is a measure of the amount of material in an object. SI uses the kilogram (kg) as the base unit. The metric system uses the gram (g) as the base unit. – One kg is equal to 2.20 pounds (lb) Length is a measure of distance. The meter (m) is the base unit slightly longer than a yard. – One m is equal to 1.09 yards (yd) Copyright © 2023 Pearson Education, Inc. All Rights Reserved Temperature (1 of 3) In general usage, temperature is considered the “hotness and coldness” of an object that determines the direction of heat flow. Heat flows spontaneously from an object with a higher temperature to an object with a lower temperature. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Temperature (2 of 3) Celsius and Kelvin scales are most often used in science. The Celsius scale is based on the properties of water. – 0 degree Celsius is the freezing point of water (0 C). – 100 degree Celsius is the boiling point of water (100 C). The Kelvin is the SI unit of temperature. – It is based on the properties of gases. – There are no negative Kelvin temperatures. – The lowest possible temperature is called absolute zero (0 K). K = degree Celsius + 273.15 Copyright © 2023 Pearson Education, Inc. All Rights Reserved Temperature (3 of 3) The Fahrenheit scale is not used in scientific measurements, but you hear about it in weather reports. The equations below allow for conversion between the Fahrenheit and Celsius scales: –  F  9 ( C)  32 5 –  C  5 ( F  32) 9 Copyright © 2023 Pearson Education, Inc. All Rights Reserved Volume Units Note that volume is not a base unit for SI; it is a derived unit from length (m m m m3 ). The most commonly used metric units for volume are the liter (L) and the milliliter (mL). – A liter is a cube, 1 decimeter (dm) long on each side. – A milliliter is a cube, 1 centimeter (cm) long on each side, also called 1 cubic centimeter (cm cm cm cm3 ). Copyright © 2023 Pearson Education, Inc. All Rights Reserved Glassware for Measuring Volume Copyright © 2023 Pearson Education, Inc. All Rights Reserved Density Density is a physical Table 1.5 Densities of Selected Substances at property of a 25°C substance. Substance Density (g/cm3 ) gram per centimeter cubed It has units that are Air 0.001 derived from the units Balsa wood 0.16 for mass and volume. Ethanol 0.79 Water 1.00 The most common Ethylene glycol 1.09 units are Table sugar 1.59 g/mL or g/cm. 3 Table salt 2.16 Iron 7.9 m D Gold 19.32 V Copyright © 2023 Pearson Education, Inc. All Rights Reserved Energy Units The unit of energy: Joule (J). It is a derived unit: 1 – KE  mv 2 2 – If the object is 2 k g , and it moves at 1 m /s , it will posses 1 J of ilo rams eter econd oule kinetic energy: 1 – 1J  (2 kg)(1 m/s)2 OR : 1 J 1 kg m 2 /s 2 2 The k J is commonly used for chemical change. ilo oule Historically, the calorie was used: 1 cal = 4.184 J. orie oules This calorie is not the nutritional calorie. That one is a k cal. ilo ories 1 nutritional calorie = 1 cal = 1000 cal. orie ories Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.6 Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy. All measured numbers have some degree of inaccuracy. The last digit measured is considered reliable, but not exact. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Numbers Encountered in Science Exact numbers are known exactly. They are counted or given by definition. – Count: there are 12 eggs in 1 dozen. – Define: 1 m = 100 c m or 1 k g = 2.2046 lb. eter enti eters ilo rams Inexact (or measured) numbers depend on how they were determined. Scientific instruments have limitations (equipment errors) and individuals can read some instrumentation differently (human errors). – Uncertainties always exist. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Precision Versus Accuracy Precision is a measure of how closely individual measurements agree with one another. Accuracy refers to how closely individual measurements agree with the correct, or “true,” value. Experimentally, we often take several measurements and determine a standard deviation. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Significant Figures All digits of a measured quantity, including the uncertain ones, are called significant figures. When rounding calculated numbers, we pay attention to significant figures so we do not overstate the accuracy of our answers. There is always uncertainty in the last digit reported for any measured quantity. If a balance measures to 0.0001 g , mass is reported as 2.2405 0.0001 g. ram Copyright © 2023 Pearson Education, Inc. All Rights Reserved Significant Figure Rules 1. All nonzero digits are significant. 2. Zeroes between nonzero digits are significant. 3. Zeroes at the beginning of a number are never significant. 4. Zeroes at the end of a number are significant if it contains a decimal point. Consider: whole numbers ending in zeroes. 1.03 10 4 g (three significant figures) 1.030 10 4 g (four significant figures) 1.0300 10 4 g (five significant figures) Copyright © 2023 Pearson Education, Inc. All Rights Reserved Significant Figures in Calculations (1 of 2) The least certain measurement limits the number of significant figures in the answer. When addition or subtraction is performed, answers are rounded to the least significant decimal place. When multiplication or division is performed, answers are rounded to the same number of digits as the measurement with the fewest number of significant figures. Note the number of appropriate digits throughout, but round off at the end only! Copyright © 2023 Pearson Education, Inc. All Rights Reserved Significant Figures in Calculations (2 of 2) Copyright © 2023 Pearson Education, Inc. All Rights Reserved 1.7 Dimensional Analysis Dimensional analysis is used to change units. We apply conversion factors (e.g., 1 in = 2.54 c m ), which are ch enti eter equalities. We can set up a ratio of comparison for the equality: 1 in. / 2.54 cm or 2.54cm / 1 in. We use the ratio which allows us to change units (puts the units we have in the denominator to cancel). We can use multiple conversions, as long as each one is an equality. Copyright © 2023 Pearson Education, Inc. All Rights Reserved Copyright This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Copyright © 2023 Pearson Education, Inc. All Rights Reserved