Chapter 1: Chemistry in Our Lives

1.1: Chemistry and Chemicals

• Chemistry: The study of the composition, structure, properties, and reactions of matter.
• Matter: The substances that make up our world.
• Chemical: A substance that always has the same composition and properties wherever it is found.
• Chemical processes take place in chemistry laboratories, manufacturing plants, and pharmaceutical labs as well as every day in nature and in our bodies.

Chemicals Commonly Used in Toothpastes

1.2: Scientific Method: Thinking Like a Scientist

• Scientific Method: A set of general principles that helps to describe how a scientist thinks.

Steps of Scientific Method

1. Observations: Information determined by noting and recording a natural phenomenon.
   • The first step in the scientific method is to make observations about nature and ask questions about what you observe.
2. Hypothesis: An unverified explanation of a natural phenomenon.
   • Propose a hypothesis, which states a possible explanation of the observations. The hypothesis must be stated in such a way that it can be tested by experiments.
3. Experiments: A procedure that tests the validity of a hypothesis.
   • Several experiments may be done to test the hypothesis.
4. Conclusion: An explanation of an observation that has been validated by repeated experiments that supports a hypothesis.
   • When the results of the experiments are analyzed, a conclusion is made as to whether the hypothesis is true or false.
   • When experiments give consistent results, the hypothesis may be confirmed.

1.3: Key Math Skills for Chemistry

• Identifying Place Values
  • For any number, we can identify the place value for each of the digits in that number.
  • These place values have names such as the one's place.
• Using Positive and Negative Numbers in Calculations
  • Positive Number: Any number that is greater than zero and has a positive sign.
  • Negative Number: Any number that is less than zero and is written with a negative sign.
• Calculating a Percentage
  • To determine a percentage, divide the parts by the total (whole) and multiply by 100%.
  • When a value is described as a percentage, it represents the number of parts of an item in 100 of those items.
• Solving Equations: In chemistry, we use equations that express the relationship between certain variables.
• Interpreting a Graph
  • Graph: Represents the relationship between two or more variables.
• Writing Numbers in Scientific Notation
  • Scientific Notation: A way of expressing numbers that are too large or too small to be conveniently written in decimal form. It has two parts:
  • a coefficient; and
  • A power of 10.