Introduction to Chemistry

1. Introduction to Chemistry Ch. 1

2. 1.1 What Is Chemistry? • What Is Chemistry? • Why is the scope of chemistry so vast?

3. 1.1 What Is Chemistry? • Matter is anything that has mass and occupies space. • Chemistry is the study of the composition of matter and the changes that matter undergoes.

4. 1.1 What Is Chemistry? • Because living and nonliving things are made of matter, chemistry affects all aspects of life and most natural events.

5. 1.3 Alchemy • Alchemy • How did alchemy lay the groundwork for chemistry?

6. 1.3 Alchemy • Alchemists developed the tools and techniques for working with chemicals.

7. 1.3 Alchemy • Alchemists developed processes for separating mixtures and purifying chemicals. They designed equipment that is still in use today including beakers, flasks, tongs, funnels, and the mortar and pestle. Mortar and Pestle

8. 1.3 The Scientific Method • The Scientific Method • What are the steps in the scientific method?

9. 1.3 The Scientific Method • The scientific method is a logical, systematic approach to the solution of a scientific problem. • Steps in the scientific method include making observations, testing hypotheses, and developing theories.

10. Observations Use one or more of the 5 senses to gather information A noting and recording of…. FACTS!!! Example: There are two computers in the room.

11. Inferences Logical interpretation based upon prior knowledge and experience Based upon observations Example: When you entered the room, you most likely inferred that the individual in the front of the room is the teacher.

12. Note the differences • In laboratory exercises, record observationsNOT inferences • Inferences may be used when writing the conclusion to your lab. • Let’s test your observation skills… • You’ll need a piece of paper and a writing utensil

14. Answer these questions Are there cars parked on the sides of the road? What color is the pickup truck driving in the road? Any minivans around? What does the green sign say? Were there any pedestrians on the road? What's the speed limit?

15. Question 1 Are there cars parked on the sides of the road?

17. Question 2 What color is the pickup truck driving in the road?

19. Question 3 Any minivans around?

21. Question 4 What does the green sign say?

23. Question 5 What's the speed limit?

25. Question 6 Are there any pedestrians on the road?

27. Observation vs. Inference On the next slide, state whether the statement is an observation or an inference.

28. 1. There is a representation of a face on one side of the coin. 2. The Latin word "Dei" means "God." 3. The coin was made by deeply religious people. 4. The date 1722 is printed on one side of the coin. 5. The coin was made in 1722. 6. The face on the coin is a representation of the nation's president.

29. Types of Observations • Qualitative observations – • Descriptive; do not involve measurement • Color, texture, smell, taste • Quantitative observations – • Measurements or counted quantities • Mass, volume, temperature, density • There are 18 students in the room • Most experiments involve both types of observations.

30. 1.3 The Scientific Method • Testing Hypotheses • A hypothesis is a proposed explanation for an observation. • You observe that a flashlight won’t work. You guess that the flashlight needs new batteries. You can test your hypothesis by putting new batteries in the flashlight. If the flashlight lights, you can be fairly certain that your hypothesis is true.

31. 1.3 The Scientific Method • An experiment is a procedure that is used to test a hypothesis. When you design experiments, you deal with variables, or factors that can change. • The variable that you change during an experiment is the manipulated variable, or independent variable. • The variable that is observed during the experiment is the responding variable, or dependent variable. • When graphing data, the independent variable goes on the X axis and the dependent on the Y axis.

32. 1.3 The Scientific Method • Developing Theories • Once a hypothesis meets the test of repeated experimentation, it may become a theory. • A theory is a well-tested explanation for a broad set of observations. • A theory may need to be changed at some point in the future to explain new observations or experimental results.

33. 1.3 The Scientific Method • Scientific Laws • A scientific law is a concise statement that summarizes the results of many observations and experiments. • A scientific law doesn’t try to explain the relationship it describes. That explanation requires a theory.

34. The Scientific Method Steps in the Scientific Method