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
| Chemical | Function |
|---|
| Calcium carbonate | Used as an abrasive to remove plaque |
| Sorbitol | Prevents loss of water and hardening of toothpaste |
| Sodium lauryl sulfate | Used to loosen plaque |
| Titanium dioxide | Makes toothpaste white and opaque |
| Triclosan | Inhibits bacteria that cause plaque and gum disease |
| Sodium fluorophosphate | Prevents formation of cavities by strengthening tooth enamel with fluoride |
| Methyl salicylate | Gives toothpaste a pleasant wintergreen flavor |
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
- 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.
- 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.
- Experiments: A procedure that tests the validity of a hypothesis.
- Several experiments may be done to test the hypothesis.
- 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.
