Introduction to Chemistry Chapter 1

Introduction to Chemistry What is chemistry? Why is it important? What do you want to learn about chemistry?

What is chemistry? Chemistry is known as the central science because it bridges other natural sciences. Chemistry is the study of matter and the changes it undergoes. Matter is defined as ANYTHING that has mass and takes up space. Because there are so many types of matter, chemistry is divided into 5 main branches. (See Table 1-1 on page 9)

5 Main Branches of Chemistry Organic chemistry: emphasis on most chemicals that contain carbon Inorganic chemistry: focuses generally on chemicals that do not contain carbon Physical chemistry: focuses on the behavior and changes of matter and the related energy changes Analytical chemistry: emphasis on the components and composition of substances Biochemistry: focuses on the matter and processes of living organisms STOP

8/9/16 Do Now “Protection from the Sun” How are these people protecting themselves from the Sun? Why is this protection important? Earth’s natural “sunscreen”

Section 1.1 The Stories of Two Chemicals

The Ozone Layer Ozone is a chemical in the Earth’s atmosphere. Earth’s atmosphere is made up of several layers (Figure on next slide) Ozone is located in the stratosphere layer of the Earth’s atmosphere. Ozone absorbs most of the ultraviolet (UV) radiation from the Sun. Ozone consists of three particles of oxygen (O 3 ).

Ozone Formation Ozone (O 3 ) is formed when oxygen gas (O 2 ) is exposed to UV radiation in the upper regions of the stratosphere.

Chlorofluorocarbons (CFCs) A CFC is a chemical that is made up of chlorine, fluorine, and carbon. CFC is a synthetic (not naturally occurring and produced in a lab), non-toxic chemical that was first created in CFCs began replacing toxic gases found in refrigerator coolants, used in air-conditioning units, and in plastic foams. In the 1970s, scientists began to notice CFCs in the atmosphere. Quantities of CFCs in the atmosphere continued to rise until a ban on products containing them went into effect in many countries. Scientists believed that CFCs were safe, but as increasingly large quantities of CFCs were collecting in the atmosphere, the ozone layer was thinning. ****Do you think there could be a connection between the two occurrences???

Section 1.3 Scientific Methods

Scientific Method Common steps of the scientific method: State the problem or question Make a hypothesis Conduct an experiment Analyze the data Draw a conclusion Share the results

Hypothesis A hypothesis is a predictive statement to provide an explanation to the problem or question being investigated during a scientific study. It is a statement of what you believe to be happening, even though there is no formal evidence at that point to support the statement

Experiment An experiment is a set of controlled observations (qualitative or quantitative) to test the hypothesis. Scientists must carefully plan and set up the laboratory experiments in order to change and test one variable at a time. Variable – quantity or condition that can have more than one value. During the experiment you will change a variable, this is called the independent variable. The dependent variable changes in response to a change in the independent variable. You cannot control or change this response without introducing bias into the experiment.

Data Analysis Since the concept of data analysis is so important, you will learn more about it in the next chapter.

Conclusion A conclusion is formed based on data analysis to determine whether your hypothesis is supported or not supported by the data. A hypothesis can never be proven.

Quiz Info 10 vocabulary questions from the word list below Chemistry Conclusion Control Dependent variable Experiment Hypothesis Independent variable Mass Matter Qualitative data Quantitative data Scientific method’ Scientific law Theory There will be 10 multiple choice question