CMC Chapter 01 - Illini West

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Chapter 1: Introduction to ChemistryChapter 1: Introduction to Chemistry

CHEMISTRY Matter and Change Section 1.1 A Story of Two Substances

Section 1.2 Chemistry and Matter

Section 1.3 Scientific Methods

Section 1.4 Scientific Research

Table Of ContentsCHAPTER

1

A Story of Two Substances

• Define substance. matter: anything that has mass and takes up space

chemistry

substance

• Explain the formation and importance of ozone.

• Describe the development of chlorofluorocarbons.

Chemistry is the study of everything around us.

SECTION

1.1

Why Study Chemistry?• All the “stuff” in the universe is made from

building blocks formed in stars.

• These building blocks and everything made from them are called matter.

• Chemistry is the study of matter and the changes it undergoes.

A Story of Two SubstancesSECTION

1.1

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The Ozone Layer

• Ultraviolet radiation damages living organisms.

• Earth’s atmosphere contains a layer of ozone that absorbs most ultraviolet radiation and protects living organisms.


1.1

The Ozone Layer (cont.)

• Ozone is a substance in the atmosphere made up of oxygen.

• A substance, also known as a chemical, is matter that has a definite composition.


1.1


• Earth’s atmosphere consists of several layers. The protective ozone layer is located in the stratosphere.


1.1


• Ozone, in the stratosphere, is formed when oxygen gas (O2) is exposed to ultraviolet radiation.


1.1

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• Ozone has interested and been studied by scientists since the late 1800’s.

• Ozone forms over the equator, where the rays of sunlight are the strongest and then flows towards the poles, thus, making it a convenient marker to follow the flow of air in the stratosphere.



1.1


• In the mid-1980s, Scientists detected thin areas in the ozone layer over Antarctica.

• What could be causing the ozone hole?


1.1

Chlorofluorocarbons• In the 1920’s, large-scale production of

refrigerators began, which used ammonia as coolant.

• In an attempt to find safer coolant, chemist, Thomas Midgley, Jr. synthesized the first chlorofluorocarbons in 1928.


1.1

• A Chlorofluorocarbon (CFC) is a substance that consists of chlorine, fluorine and carbon.

Chlorofluorocarbons (cont.)

• Because of being nontoxic and very stable, they seemed to be ideal coolants for refrigerators and AC units, for use in plastic foams and as propellants in spray cans.


1.1

• All substances that are classified as CFCs are:–Man-made (they do not occur naturally)–Nontoxic–Stable (they do not readily react with other substances)

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Chlorofluorocarbons (cont.)

• CFCs were first detected in the atmosphere in the 1970s, and the concentrations continued to increase through the 1990s.

• Could there be a connection between ozone thinning and increasing CFCs in the atmosphere?


1.1 A Story of Two Substances

• Define substance.

• Explain the formation and importance of ozone.

• Describe the development of chlorofluorocarbons.

SECTION

1.1

• Compare and contrastmass and weight.

technology: a practical application of scientific information.

massweightmodel

• Explain why chemists are interested in a submicroscopic description of matter.

• Identify the area of emphasis for various branches of chemistry.

Branches of chemistry involve the study of different kinds of matter.

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1.2 Chemistry and Matter

Matter and its Characteristics• Matter is anything that has mass and takes

up space.• Mass is a measurement that reflects the

amount of matter.

• Weight is a measure of mass and the force of gravity on an object.

• Weight can change from place to place, but mass is constant.

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Matter and its Characteristics (cont.)

• Much of matter and its behavior is macroscopic, meaning that it can be observed without a microscope.

• The structure, composition, and behavior of all matter can be described on the submicroscopic (atomic) level.

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• Chemistry explains events on the atomic level (submicroscopic) that cause macroscopic observations.

• A model is a verbal, visual, or mathematical explanation of experimental data.

Matter and its Characteristics (cont.)

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• Chemistry is traditionally broken into branches that focus on specific areas such as:

– Organic chemistry

– Inorganic chemistry

– Physical chemistry

– Analytical chemistry

– Biochemistry

– Environmental chemistry

Chemistry: The Central Science

– Industrial chemistry

– Polymer chemistry

– Theoretical chemistry

– Thermochemistry

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Chemistry: The Central Science (cont.)

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• Compare and contrast mass and weight.

• Explain why chemists are interested in a submicroscopic description of matter.

• Identify the area of emphasis for various branches of chemistry.

SECTION


• Identify the common steps of scientific methods.

• Compare and contrast types of data.

• Identify types of variables.

• Describe the difference between a theory and a scientific law.

systematic approach: an organized method of solving a problem.

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1.3 Scientific Methods

scientific methodqualitative dataquantitative datahypothesisexperimentindependent variable

Scientists use scientific methods to systematically pose and test solutions to questions and assess the results of the tests.

dependent variablecontrolconclusiontheoryscientific law

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A Systematic Approach• The scientific method is a systematic

approach used in scientific study, whether it is chemistry, physics, biology, or another science.

• It is an organized process used by scientists to do research, and provides methods for scientists to verify the work of others.

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A Systematic Approach (cont.)

• The steps in a scientific method are repeated until a hypothesis is supported or discarded.

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• An observation is the act of gathering information.– Qualitative data is obtained through observations that

describe color, smell, shape, or some other physical characteristic that is related to the five senses.

– Quantitative data is obtained from numerical observations that describe how much, how little, how big or how fast.


• Recall in section1, Scientists observed that there were CFCs in the atmosphere and that their levels were increasing.

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• A hypothesis is a tentative explanation for what has been observed.–Scientists hypothesized that CFCs, although stable,

break down in the stratosphere due to interactions with ultraviolet radiation from the Sun, and that the chlorine produced by this interaction would break down ozone.

• An experiment is a set of controlled observations that test the hypothesis.


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• A variable is a quantity or condition that can have more than one value.

– An independent variable is the variable you plan to change.

– The dependent variable is the variable that changes in value in response to a change in the independent variable.

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• If you were trying to determine if temperature affects bacterial growth, you would expose different petri dishes of the same bacteria to different temperatures.– Temperature is your independent variable.– Bacteria growth is your dependent variable.

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• A control is a standard for comparison in the experiment.–During clinical drug trials, physicians will use a double-

blind study. They use two statistically identical groups of patients. One will receive the drug and one will receive a placebo. Neither patient or physician will know which group receives the drug.

–The group receiving the placebo is the control group.

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• A conclusion is a judgment based on the information obtained from the experiment.

– A hypothesis is never proven, only supported or discarded.

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• Scientists, Molina and Rowland, formed a hypothesis about the stability of CFCs in the stratosphere. They gathered data that supported their hypothesis and developed a model in which chlorine formed by the breakdown of CFCs would react over and over again with ozone.


– A model can be used to make predictions.

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• Molina and Rowland’s model showed how CFCs could destroy ozone.


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• A theory is an explanation that has been repeatedly supported by many experiments.

– A theory states a broad principle of nature that has been supported over time by repeated testing.

– Theories are successful if they can be used to make predictions that are true.

Theory and Scientific Law

SECTION


• A scientific law is a relationship in nature that is supported by many experiments, and no exceptions to these relationships are found.

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Theory and Scientific Law (cont.)

• Identify the common steps of scientific methods.

• Compare and contrast types of data.

• Identify types of variables.

• Describe the difference between a theory and a scientific law.

SECTION


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• Compare and contrast pure research, applied research, and technology.

synthetic: something that is human-made and does not necessarily occur in nature

pure researchapplied research

• Apply knowledge of laboratory safety.

Some scientific investigations result in the development of technology that can improve our lives and the world around us.

SECTION

1.4 Scientific Research

Types of Scientific Investigations• Pure research is research to gain

knowledge for the sake of knowledge itself.–Molina and Rowland were motivated by curiosity

when they conducted their research on CFCs and their interactions with ozone.

–No environmental evidence at the time indicated that there was a correlation to their model in the stratosphere

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Types of Scientific Investigations (cont.)

• Applied research is research undertaken to solve a specific problem.–Scientists continue to monitor the amount of CFCs in

the atmosphere and the annual changes in the amount of ozone in the stratosphere.

–Scientists continue to conduct research to find replacement chemicals for CFCs that are now banned.

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• Chance discoveries occur when scientists obtain results that are far different from what they expected.– Ex. Alexander Fleming’s discovery of Penicillin.

Types of Scientific Investigations (cont.)

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Students in the Laboratory• You are responsible for your safety and the

safety of others around you.

• Refer to Table 1.2 on page 19 of your textbook for a list of safety rules in the laboratory.

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• Applied research showed that CFCs and a few other chemicals react with ozone.

• Many nations agreed in 1987 to the Montreal Protocol, to phase out CFC use.

The Story Continues

SECTION


• Scientists have learned the ozone thinning occurs over Antarctica every spring.

SECTION


The Story Continues (cont.)

• Chemists solve many real problems we face today such as:

– Ozone depletion

– Finding cures for diseases

– Reducing automobile pollution

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The Benefits of Chemistry

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• Compare and contrast pure research, applied research, and technology.

• Apply knowledge of laboratory safety.

SECTION


CMC Chapter 01 - Illini West

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