Chapter 1. Introduction to Chemistry

1.1 Chemistry: An Introduction 1.2 What is Chemistry? 1.3 Solving Problems Using a Scientific Approach 1.4 The Scientific Method 1.5 Learning Chemistry Copyright © Cengage Learning. All rights reserved

Why Is Chemistry Important? Copyright © Cengage Learning. All rights reserved

Graphite and Diamond (C) Ice cubes in water (H2O) Graphite and Diamond (C) Copyright © Cengage Learning. All rights reserved

New materials New pharmaceuticals New energy sources Food supplies Help the environment Copyright © Cengage Learning. All rights reserved

Double-edged sword Solve the problems… CHLOROFLUOROCARBONS (CFCs) Freon-12---noncorrosive nature and ability to resist decomposition Solve the problems… Freon-12---destroy ozone (O3)in the upper atmosphere. Copyright © Cengage Learning. All rights reserved

In this course, you will: Learn the principles of chemistry. Become a better problem solver! Copyright © Cengage Learning. All rights reserved

QUESTION Which of the following statements is false? A knowledge of chemistry is useful to almost everyone. The principles of chemistry are inherently neither good nor bad – it’s what we do with this knowledge that really matters. A major by-product of studying chemistry is that you will become a better problem solver. Chemical industries are the ones responsible for all our environmental problems today.

ANSWER Choice #4 is false. Although chemical industries have contributed to some environmental problems, they are not responsible for all of them. The industries that apply the chemical sciences are now determined to be part of the solution to our environmental ills rather than part of the problem. : Chemistry: An Introduction

The science that deals with the materials of the universe and the changes these materials undergo. (Chemical changes) The central science. Understanding most other fields of science requires an understanding of chemistry. 1.Wood burns in air, forming water, carbon dioxide and other substances. 2. Eggs, flour, sugar and baker powder are mixed and baked to yield a cake. 3. The definition of the term chemistry is learned and stored in the brain. Copyright © Cengage Learning. All rights reserved

Recognize the problem and state it clearly. Making an observation. Copyright © Cengage Learning. All rights reserved

Formulating a hypothesis. 2. Propose possible solutions to the problem or possible explanations for the observation. Formulating a hypothesis. Copyright © Cengage Learning. All rights reserved

Performing an experiment. 3. Decide which of the solutions is the best or decide whether the explanation proposed is reasonable. Performing an experiment. Scientific thinking can help you in all parts of your life! Copyright © Cengage Learning. All rights reserved

Steps in the Scientific Method Process that lies at the center of scientific inquiry. The difference between observations and theories. An observation is something is witnessed and can be recorded. A theory is an interpretation-a possible explanation of why nature behaves in a particular way. The difference between a Law and a theory. A law tells what happens A theory (model) is our attempt to explain why it happens. Copyright © Cengage Learning. All rights reserved

QUESTION Which of the following statements is false? A law is a summary of observed behavior. For example, studies of innumerable chemical changes have shown that the total mass of the materials involved is the same before and after the change. A theory is an explanation of behavior – why nature behaves in a particular way. If a theory is disproven, then all of the observations that support that theory must also be disproven. A law tells what happens.

ANSWER Choice #3 is false. A theory can be wrong in its attempt to explain why a behavior occurs but that does not mean that the observed behavior in itself is also wrong. : The Scientific Method

Summarizes what happens. Scientific Models Law Summarizes what happens. Hypothesis A possible explanation for an observation. Theory (Model) An attempt to explain why it happens. Set of tested hypotheses that gives an overall explanation of some natural phenomenon. Copyright © Cengage Learning. All rights reserved

Memorize important information. Learn and practice processes. Learn the vocabulary. Memorize important information. Learn and practice processes. Keep working and learning from your mistakes. Ask questions! Copyright © Cengage Learning. All rights reserved

Prerequisite Science Skills

2.3 Measurements of Length, Volume, and Mass 2.1 Scientific Notation 2.2 Units 2.3 Measurements of Length, Volume, and Mass 2.4 Uncertainty in Measurement 2.5 Significant Figures 2.6 Problem Solving and Dimensional Analysis 2.7 Temperature Conversions: An Approach to Problem Solving 2.8 Density Copyright © Cengage Learning. All rights reserved 20

Quantitative observation. Has 2 parts – number and unit. Measurement Quantitative observation. Has 2 parts – number and unit. Number tells comparison. Unit tells scale. Copyright © Cengage Learning. All rights reserved 21

Technique used to express very large or very small numbers. Expresses a number as a product of a number between 1 and 10 and the appropriate power of 10. Copyright © Cengage Learning. All rights reserved 22

This depends on the number of places the decimal point is moved and in which direction.

Using Scientific Notation If the decimal point is moved to the left, the power of 10 is positive. 345 = 3.45 × 102 If the decimal point is moved to the right, the power of 10 is negative. 0.0671 = 6.71 × 10–2 Copyright © Cengage Learning. All rights reserved 24

Concept Check Which of the following correctly expresses 7,882 in scientific notation? 7.882 × 104 788.2 × 103 7.882 × 103 7.882 × 10–3 The correct answer is c. The decimal point should be moved three places to the left to be correctly expressed in scientific notation. Copyright © Cengage Learning. All rights reserved 25

Concept Check Which of the following correctly expresses 0.0000496 in scientific notation? 4.96 × 10–5 4.96 × 105 4.96 × 10–7 496 × 107 The correct answer is a. The decimal point should be moved five places to the right to be correctly expressed in scientific notation. Copyright © Cengage Learning. All rights reserved 26 26

Math Review Copyright © Cengage Learning. All rights reserved

Copyright © Cengage Learning. All rights reserved

Quantitative observation consisting of two parts. number Nature of Measurement Measurement Quantitative observation consisting of two parts. number unit : tell scale or standard is being used to represent the results of the measurement. Examples 20 grams 70 miles/hour Copyright © Cengage Learning. All rights reserved 29

The Fundamental SI Units SI Units: the need for common units standards The Fundamental SI Units Physical Quantity Name of Unit Abbreviation Mass kilogram kg Length meter m Time second s Temperature kelvin K Electric current ampere A Amount of substance mole mol Copyright © Cengage Learning. All rights reserved 30

Prefixes Used in the SI System Prefixes are used to change the size of the unit. Copyright © Cengage Learning. All rights reserved 31

Length (SI unit: meter) Fundamental SI unit of length is the meter. Copyright © Cengage Learning. All rights reserved 32

Conversion between inch and cm: 1 inch = 2.54 cm Copyright © Cengage Learning. All rights reserved

Volume (SI unit: cubic meter, m3) Measure of the amount of 3-D space occupied by a substance. Commonly measure solid volume in cm3. 1 mL = 1 cm3 1 L = 1 dm3 Copyright © Cengage Learning. All rights reserved 34

Pipet, mL Graduated Cylinders mL “zero was at the bottom of the scale, with values increasing going up the cylinder. “ a buret has zero at the top with values increasing going down the scale. Buret, mL Copyright © Cengage Learning. All rights reserved

Mass (SI unit: kilogram, kg) Measure of the amount of matter present in an object. 1 kg = 2.2046 lbs 1 lb = 453.59 g Copyright © Cengage Learning. All rights reserved 36

Triple beam balance Electronic balance Analytical balance Copyright © Cengage Learning. All rights reserved