Chapter 1. Matter, Measurement, and Problem Solving

1. Chapter 1. Matter, Measurement, and Problem Solving CHE 123: General Chemistry I Dr. Jerome K. Williams, Ph.D. Saint Leo University

2. Introductory Remarks Why Study Chemistry? What is Chemistry? Tro: Chemistry: A Molecular Approach, 2/e

3. Why Study Chemistry? • Chemistry is Everywhere! • The Central Science • Two Reasons • Bridge linking many disciplines • Important not just to chemists

4. What is Chemistry? • Chemistry is the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules.

5. Composition of Matter Atoms and Molecules Scientific Method Tro: Chemistry: A Molecular Approach, 2/e

6. Structure Determines Properties carbon dioxide carbon monoxide • composed of one carbon atom and two oxygen atoms • colorless, odorless gas • incombustible • does not bind to hemoglobin • composed of one carbon atom and one oxygen atom • colorless, odorless gas • burns with a blue flame • binds to hemoglobin • The properties of matter are determined by the atoms and molecules that compose it Tro: Chemistry: A Molecular Approach, 2/e 6

7. Atoms and Molecules Atoms submicroscopic particles fundamental building blocks of ordinary matter “Letters” in chemical alphabet Molecules two or more atoms attached together in a specific geometrical arrangement attachments are called bonds attachments come in different strengths come in different shapes and patterns “Words” in our chemical language Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 7

8. The Language of Chemistry

9. Language of Chemistry • Letters → Words→ Sentences • Atoms → Molecules→ Reactions

10. The Scientific Approach to Knowledge Philosophers try to understand the universe by reasoning and thinking about “ideal” behavior Scientists try to understand the universe through empirical knowledge gained through observation and experiment Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 10

11. Gathering Empirical Knowledge ─ Observation • Some observations are descriptions of the characteristics or behavior of nature ─qualitative • “The soda pop is a liquid with a brown color and a sweet taste. Bubbles are seen floating up through it.” • Some observations compare a characteristic to a standard numerical scale ─quantitative • “A 240 mL serving of soda pop contains 27 g of sugar.” Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 11

12. From Observation to Understanding • Hypothesis– a tentative interpretation or explanation for an observation • “The sweet taste of soda pop is due to the presence of sugar.” • A good hypothesis is one that can be tested to be proved wrong! • falsifiable • one test may invalidate your hypothesis Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 12

13. Testing Ideas Ideas in science are tested with experiments An experiment is a set of highly controlled procedures designed to test whether an idea about nature is valid The experiment generates observations that will either validate or invalidate the idea Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 13

14. From Specific to General Observations • A scientific lawis a statement that summarizes all past observations and predicts future observations • Law of Conservation of Mass–“In a chemical reaction matter is neither created nor destroyed.” • A scientific law allows you to predict future observations • so you can test the law with experiments Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 14

15. From Specific to General Understanding A hypothesis is a potential explanation for a single or small number of observations A scientific theory is a general explanation for why things in nature are the way they are and behave the way they do models pinnacle of scientific knowledge validated or invalidated by experiment and observation Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 15

16. Scientific Method Procedure designed to test an idea Tentative explanation of a single or small number of observations General explanation of natural phenomena Careful noting and recording of natural phenomena Generally observed occurence in nature Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 16

17. Relationships Between Pieces of the Scientific Method Tro: Chemistry: A Molecular Approach Tro: Chemistry: A Molecular Approach, 2/e 17