Lecture Presentation

Chapter 1

Chemistry in Our Lives

Forensic scientists work in crime laboratories where they analyze bodily fluids and tissue samples collected by the crime scene investigators.

Jobs in Chemistry

Learning Goal Define the term chemistry and identify substances as chemicals.

Chemists working in laboratories test new products and develop new pharmaceuticals.

1.1 Chemistry and Chemicals

Chemistry: • is the study of composition,

structure, properties, and reactions of matter.

• happens all around you every day.

What is Chemistry?

Antacid tablets undergo a chemical reaction when dropped in water.

Matter is another word for all substances that make up our world.

• Antacid tablets are matter.

• Water is matter.

• Glass is matter.

• Air is matter.

Chemistry and Matter

Chemicals are

• Substances (aka matter) that have the same composition and properties wherever they are found.

• often substances made by chemists that you use every day. Toothpaste is a combination

of many chemicals.

Chemicals

Chemicals in Toothpaste

Chemicals in the Kitchen

Which of the following contains chemicals?

A. Sunlight

B. Fruit

C. Milk

D. Breakfast cereal

Study Check

Learning Goal Describe the activities that are part of the scientific method.

Thinking Like a ScientistLinus Pauling won the Nobel Prize in chemistry in 1954.

1.2 Scientific Method

The scientific method is a set of general principles that helps to describe how a scientist thinks.

1. Make observations about nature and ask questions about what you observe.

2. Propose a hypothesis, which states a possible explanation of the observations.

3. Several experiments may be done to test the hypothesis.

4. When results of the experiments are analyzed, a conclusion is made as to whether the hypothesis may be true or false.

The Scientific Method

Suppose you visit a friend in her home and soon after you arrive, you begin to sneeze.

• You observe that your friend has a new cat.

• You ask yourself why you are sneezing and form a hypothesis that you are allergic to cats.

• You perform experiments to test your hypothesis by visiting other friends with cats.

• If you sneeze after leaving the other homes with cats, you come to the conclusion that your hypothesis is correct.

Using the Scientific Method

Through your observations, you may determine that you are allergic to cat hair and dander.

Using the Scientific Method

The scientific method develops conclusions using observations, hypotheses, and experiments.

The hypothesis is modified if the results of the experiments do not support it.

Using the Scientific Method

Identify each of the following as an observation (O), a hypothesis (H), an experiment (E), or a conclusion (C):A. During your visit to the gym, your trainer records that you

ran for 25 minutes on the treadmill.B. Scientific studies show that exercising lowers blood

pressure.C. Your doctor thinks that your weight loss is due to

increased exercise.

Study Check

Studying in a group can be beneficial to learning.

Learning Goal Develop a study plan for learning chemistry.

1.3 Learning Chemistry: A Study Plan

My study plan for learning chemistry will include the following:• reading the chapter before lectures• going to lectures and being an active learner in

lectures• keeping a problem notebook• reading the text or lecture slides as an active learner• working the Practice Problems and checking the

answers

Making a Study Plan

• organizing a study group• seeing the instructor during

tutoring• attending study groups• organizing study groups• studying often

Making a Study Plan (continued)

Which of the following activities should be included in your study plan for learning chemistry?A. Skipping lectures B. Forming a study groupC. Keeping a problem notebook D. Reading the text as an active learner

Study Check

Learning Goal Review math concepts used in chemistry: place values, positive and negative numbers, percentages, solving equations, interpreting graphs, and writing numbers in scientific notation.

A graph represents the relationship between two variables.

1.4 Key Math Skills for Chemistry

For any number, we can identify the place value for each of the digits in that number.The place values for two numbers are listed below:

Key Math Skill Identifying Place Values

A premature baby has a mass of 2518 grams.

A silver coin has a mass of 6.407 grams.

A. Identifying Place Values

To determine a percentage, divide the parts by the total (whole) and multiply by 100%.

𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑 =𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒕𝒕𝒑𝒑𝒑𝒑𝒕𝒕

𝒙𝒙 𝟏𝟏𝟏𝟏𝟏𝟏

If you have 100 balls and 5 are red, what percentage of balls are red?

Key Math Skill Calculating Percentages

C. Calculating Percentages

Equations can be rearranged to solve for an unknown variable.

𝟐𝟐𝒙𝒙 + 𝟖𝟖 = 𝟏𝟏𝟏𝟏1. Place all like items on one side.

2. Isolate the variable you need to solve for.

3. Check your answer.

Key Math Skill Solving Equations

D. Solving Equations

Solve the following equation for P1.

Study Check

A graph • represents the relationship between two

variables.• contains two perpendicular axes.• has a horizontal axis, or x axis.• has a vertical axis, or y axis.

Key Math Skill Interpreting Graphs

E. Interpreting Graphs

In the following graph, the• volume of a gas in a balloon is plotted against its

temperature.• y axis represents the volume (L) of the gas in the

balloon.• x axis represents the temperature (°C) of the gas.• title indicates that the volume of the balloon was

measured at different temperatures.• points represent the volume of gas that was

measured at a specific temperature.

Interpreting Graphs

The line on the graph • indicates a direct

relationship: that the volume of a gas in a balloon increases with increasing temperature.

• can be used to determine the gas volume at various temperatures.

Interpreting Graphs

People have an average of 1 × 105 hairs on the scalp. Each hair is about 8 × 10−6 m wide.

Key Math Skill Writing Numbers in Scientific Notation

F. Scientific Notation

Some Positive Powers of 10

Some Negative Powers of 10

2 400

0.00086

Scientific Notation

Numbers written in scientific notation have two parts:

Coefficient Power of 10

Scientific Notation

Diameter of chickenpox virus = 0.000 000 3 m= 3 × 10−7 m

Measurements in Scientific Notation

Some Measurements Written in Scientific Notation

Numbers in scientific notation can be entered into a calculator using the EXP or EE key.

Scientific Notation and Calculators

Guide to Writing a Number in Scientific Notation

Write each of the following in correct scientific notation:

A. 64 000

B. 0.021

Study Check

Concept Map