ChemistryToombs County High School

What Is Chemistry? Why is the scope of chemistry so vast?

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Matter is anything that has mass and occupies space.

Chemistry is the study of the composition and properties of matter and the changes that matter undergoes.

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Because living and nonliving things are made of matter, chemistry affects all aspects of life and most natural events.

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Areas of StudyWhat are five traditional areas of study in chemistry?

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Five traditional areas of study are ▪organic chemistry▪inorganic chemistry▪biochemistry ▪analytical chemistry ▪physical chemistry

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Organic chemistry is defined as the study of all chemicals containing carbon.

Inorganic chemistry is the study of chemicals that, in general, do not contain carbon.

The study of processes that take place in organisms is biochemistry.

Analytical chemistry is the area of study that focuses on the composition of matter.

Physical chemistry is the area that deals with the mechanism, the rate, and the energy transfer that occurs when matter undergoes a change.

Pure and Applied ChemistryHow are pure and applied chemistry related?

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Pure chemistry is the pursuit of chemical knowledge for its own sake.

Applied chemistry is research that is directed toward a practical goal or application.

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Pure research can lead directly to an application, but an application can exist before research is done to explain how it works.

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Nylon In the early 1930’s,

Wallace Carothers produced nylon while researching cotton and silk.

A team of scientists and engineers applied Carothers’s research to the commercial production of nylon.

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Aspirin▪ Long before researchers figured out

how aspirin works, people used it to relieve pain, and doctors prescribed it for patients who were at risk for a heart attack.

▪ In 1971, it was discovered that aspirin can block the production of a group of chemicals that cause pain and lead to the formation of blood clots. This is an example of pure research.

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Technology is the means by which a society provides its members with those things needed and desired.

▪Technology allows humans to do some things more quickly or with less effort.

▪There are debates about the risks and benefits of technology.

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Why Study Chemistry?What are three general reasons to study chemistry?

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Chemistry can be useful in explaining the natural world, preparing people for career opportunities, and producing informed citizens.

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Explaining the Natural WorldChemistry can help you satisfy your natural desire to understand how things work.

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Preparing For a Career Many careers require knowledge of

chemistry. A photographer uses chemical processes to control the development of photographs in a darkroom.

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Being an Informed Citizen Knowledge of chemistry

and other sciences can help you evaluate the data presented, arrive at an informed opinion, and take appropriate action.

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MaterialsWhat impact do chemists have on materials, energy, medicine, agriculture, the environment, and the study of the universe?

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Chemists design materials to fit specific needs.

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In 1948, George de Mestral took a close look at the burrs that stuck to his clothing. He saw that each burr was covered with many tiny hooks.

In 1955, de Mestral patented the design for the hook-and-loop tapes. These are used as fasteners in shoes and gloves.

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This story illustrates two ways of looking at the world—the macroscopic view and the microscopic view. Burrs belong to the macroscopic world,

the world of objects that are large enough to see with the unaided eye.

The hooks belong to the microscopic world, or the world of objects that can be seen only under magnification.

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EnergyChemists play an essential role in finding ways to conserve energy, produce energy, and store energy.

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Conservation One of the easiest ways to conserve energy is through insulation. Insulation acts as a barrier to heat flow from the inside to the outside of a house or from the outside to the inside of a freezer.

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▪ SEAgel is a modern insulation that is light enough to float on soap bubbles.

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Production▪ The burning of coal, petroleum, and

natural gas is a major source of energy. These materials are called fossil fuels. Oil from the soybeans is used to make biodiesel.

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Storage▪ Batteries are devices that use chemicals to store energy that will be released as electric current.

▪ For some applications, it important to have batteries that can be recharged rather than thrown away. Digital cameras, wireless phones, and laptop computers use rechargeable batteries.

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Medicine and Biotechnology

Chemistry supplies the medicines, materials, and technology that doctors use to treat their patients.

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Medicines There are over 2000 prescription drugs. Many drugs are effective because they interact in a specific way with chemicals in cells. Knowledge of the structure and function of these target chemicals helps a chemist design safe and effective drugs.

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Materials Chemistry can supply materials to repair or replace body parts. Artificial hips and knees made from metals and plastics can replace worn-out joints and allow people to walk again without pain.

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Biotechnology From 1990 to 2003,

scientists worldwide worked on the Human Genome Project. They identified the genes that comprise human DNA—about 30,000. The discovery of the structure of DNA led to the development of biotechnology.

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Biotechnology applies science to the production of biological products or processes.

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AgricultureChemists help to develop more productive crops and safer, more effective ways to protect crops.

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Productivity One way to track productivity is to measure the amount of edible food that is grown on a given unit of land.

Chemists test soil to see if it contains the right chemicals to grow a particular crop and recommend ways to improve the soil.

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Chemists also help determine when a crop needs water.

If the genes from a jellyfish that glows are transferred to a potato plant, the plant glows when it needs to be watered.

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Crop Protection Chemists sometimes use chemicals

produced by insects to fight insect pests. The plastic tube wrapped around the stem of the tomato plant contains a chemical that a female pinworm moth emits to attract male moths. It interferes with the mating process so that fewer pinworms are produced.

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The Environment

▪A pollutant is a material found in air, water, or soil that is harmful to humans or other organisms.▪Chemists help to identify pollutants and prevent pollution.

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Identify Pollutants Until the mid-1900s, lead was used in

many products, including paints and gasoline.

A study done in 1971 showed that the level of lead that is harmful to humans is much lower than had been thought, especially for children. Even low levels of lead in the blood can permanently damage the nervous system of a growing child.

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Prevent Pollution The strategies used to

prevent lead poisoning include testing children’s blood for lead, regulation of home sales to families with young children, and public awareness campaigns with posters.

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The percentage of children with elevated blood levels has decreased since the 1970s.

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The UniverseTo study the universe, chemists gather data from afar and analyze matter that is brought back to Earth.

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Chemists have analyzed more than 850 pounds of moon rocks that were brought back to Earth. Some of these rocks are similar to rocks formed by volcanoes on Earth, suggesting that vast oceans of molten lava once covered the moon's surface.

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▪ The robotic vehicle Opportunity was designed to determine the chemical composition of rocks and soil on Mars. Data collected at the vehicle’s landing site indicated that the site was once drenched with water.

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In 1928, Alexander Fleming noticed that bacteria he was studying did not grow in the presence of a yellow-green mold. In 1945, Fleming shared a Nobel Prize for Medicine with Howard Florey and Ernst Chain, who led the team that isolated penicillin.

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Alchemy How did alchemy lay the groundwork for chemistry?

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Alchemists developed the tools and techniques for working with chemicals.

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Alchemists developed processes for separating mixtures and purifying chemicals. They designed equipment that is still in use today including beakers, flasks, tongs, funnels, and the mortar and pestle.

Mortar and Pestle

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An Experimental Approach to ScienceHow did Lavoisier help to transform chemistry?

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Lavoisier helped to transform chemistry from a science of observation to the science of measurement that it is today.

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Lavoisier designed a balance that could measure mass to the nearest 0.0005 gram. He also showed that oxygen is required for a material to burn.Reconstruction of Lavoisier’s Laboratory

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The Scientific MethodWhat are the steps in the scientific method?

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▪ The scientific method is a logical, systematic approach to the solution of a scientific problem.

▪ Steps in the scientific method include making observations, testing hypotheses, and developing theories.

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Making Observations When you use your

senses to obtain information, you make an observation.

Suppose you try to turn on a flashlight and it does not light. An observation can lead to a question: What’s wrong with the flashlight?

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Testing Hypotheses A hypothesis is a proposed

explanation for an observation. You guess that the flashlight needs

new batteries. You can test your hypothesis by putting new batteries in the flashlight. If the flashlight lights, you can be fairly certain that your hypothesis is true.

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An experiment is a procedure that is used to test a hypothesis. When you design experiments, you deal with variables, or factors that can change. The variable that you change during an

experiment is the manipulated variable, or independent variable.

The variable that is observed during the experiment is the responding variable, or dependent variable.

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Developing Theories▪ Once a hypothesis meets the test of repeated experimentation, it may become a theory.▪ A theory is a well-tested explanation for a broad set of observations.

▪ A theory may need to be changed at some point in the future to explain new observations or experimental results.

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Scientific Laws A scientific law is a concise statement that summarizes the results of many observations and experiments.

A scientific law doesn’t try to explain the relationship it describes. That explanation requires a theory.

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Steps in the Scientific Method

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Collaboration and Communication What role do collaboration and communication play in science?

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No matter how talented the players on a team, one player cannot ensure victory for the team. Individuals must collaborate, or work together, for the good of the team. When scientists collaborate and

communicate, they increase the likelihood of a successful outcome.

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Collaboration Scientists choose to collaborate for different reasons. ▪ Some research problems are so complex that no one person could have all of the knowledge, skills, and resources to solve the problem.

▪ Scientists might conduct research for an industry in exchange for equipment and the time to do the research.

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Collaboration isn’t always a smooth process. You will likely work on a team in the laboratory. If so, you may face some challenges. But you can also experience the benefits of collaboration.

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Communication Scientists communicate

face to face, by e-mail, by phone, and at international conferences.

Scientists publish their results in scientific journals. Articles are published only after being reviewed by experts in the author’s field.

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Shape-sorter toys fascinate young children. Typically, the children try placing a shape in different holes until they find the right one. The trial-and-error approach is one method of problem solving, but it is usually not the best one.

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Skills Used in Solving Problems What is a general approach to solving a

problem?

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▪Effective problem solving always involves developing a plan and then implementing that plan.

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Shopping involves problem solving skills.

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Solving Numeric Problems What are the three steps for solving

numeric problems?

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The steps for solving a numeric word problem are analyze, calculate, and evaluate.

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Analyze To solve a word problem, you must first determine where you are starting from (identify what is known) and where you are going (identify the unknown).

After you identify the known and the unknown, you need to make a plan for getting from the known to the unknown.

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Calculate If you make an effective plan, doing

the calculations is usually the easiest part of the process.

Evaluate Check that your answer is reasonable

and makes sense. Check that it has the correct unit and the correct number of significant figures.

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Figure 1.25 Map of Indianapolis

Solving Conceptual ProblemsWhat are the two steps for solving conceptual problems?

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The steps for solving a conceptual problem are analyze and solve.

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Problem Solving 1.29 Solve Problem 29 with the help of an interactive guided tutorial.

Bamboo has properties that make it a good choice for use in chopsticks. It has no noticeable odor or taste. It is hard, yet easy to split, and it is heat resistant. You will learn how properties can be used to classify and identify matter.

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Describing MatterHow can properties used to describe matter be classified?

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Properties used to describe matter can be classified as extensive or intensive.

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Extensive Properties The mass of an object is a measure

of the amount of matter the object contains.

The volume of an object is a measure of the space occupied by the object.

An extensive property is a property that depends on the amount of matter in a sample.

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Intensive Properties▪ An intensive property is a property that depends on the type of matter in a sample, not the amount of matter. The hardness of a bowling ball is an example of an intensive property.

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Identifying SubstancesWhy do all samples of a substance have the same intensive properties?

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Matter that has a uniform and definite composition is called a substance. These kettles are mainly copper. Copper is an example of a substance.

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▪ This sculpture of a falcon is made of gold. Gold is an example of a substance.

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Every sample of a given substance has identical intensive properties because every sample has the same composition.

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▪A physical property is a quality or condition of a substance that can be observed or measured without changing the substance’s composition.

▪Hardness, color, conductivity, and malleability are examples of physical properties.

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States of MatterWhat are three states of matter?

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Three states of matter are solid, liquid, and gas.

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Solids▪A solid is a form of matter that has a definite shape and volume.

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Liquid▪ A liquid is a form of matter that has an indefinite shape, flows, yet has a fixed volume.

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Gases▪A gas is a form of matter that takes both the shape and volume of its container.

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▪Vapor describes the gaseous state of a substance that is generally a liquid or solid at room temperature, as in water vapor.

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Physical ChangesHow can physical changes be classified?

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During a physical change, some properties of a material change, but the composition of the material does not change.

As gallium melts in a person’s hand, the shape of the sample changes, but the composition of the material does not change.

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Physical changes can be classified as reversible or irreversible.

▪ All physical changes that involve a change from one state to another are reversible.

▪ Cutting hair, filing nails, and cracking an egg are examples of irreversible physical changes.

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Panning is one way to separate gold from a mixture of gold and materials such as sand or gravel. A pan containing the mixture is place underwater and shaken vigorously from left to right. You will learn how to classify and separate mixtures.

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Classifying MixturesHow can mixtures be classified?

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▪ A mixture is a physical blend of two or more components.

▪ A salad bar provides a range of items. Customers choose how much of each item to use in their salads. Each salad has a different composition.

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Based on the distribution of their components, mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures.

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Heterogeneous Mixtures▪A mixture in which the composition is not uniform throughout is a heterogeneous mixture.

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Homogeneous Mixtures▪A mixture in which the composition is uniform throughout is a homogeneous mixture.

▪Another name for a homogeneous mixture is a solution.

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▪ The term phase is used to describe any part of a sample with uniform composition and properties.▪A homogenous mixture consists of a single phase.

▪A heterogeneous mixture consists of two or more phases.

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▪When oil and vinegar are mixed they form layers, or phases. The oil phase floats on the water phase.

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Separating Mixtures How can mixtures be separated?

Differences in physical properties can be used to separate mixtures.

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Filtration▪ The process that separates a solid from the

liquid in a heterogeneous mixture is called filtration.

▪ A colander is used to separate pasta from the water in which it was cooked. This process is a type of filtration.

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Distillation▪ During a distillation, a liquid is boiled to

produce a vapor that is then condensed into a liquid.

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Take two pounds of sugar, two cups of boiling water, and one quarter teaspoon of cream of tartar. Add food coloring and you have the sticky, sweet concoction known as cotton candy. You will learn how substances are classified as elements or compounds.

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Distinguishing Elements and Compounds How are elements and compounds different?

An element is the simplest form of matter that has a unique set of properties.

A compound is a substance that contains two or more elements chemically combined in a fixed proportion.

Compounds can be broken down into simpler substances by chemical means, but elements cannot.

Breaking Down Compounds A chemical change is a

change that produces matter with a different composition than the original matter.

When table sugar is heated, it goes through a series of chemical changes.

▪ The final products of these chemical changes are solid carbon and water vapor. The following diagram summarizes the process.

Properties of Compounds

▪ In general, the properties of compounds are quite different from those of their component elements.

▪ When the elements sodium and chlorine combine chemically to form sodium chloride, there is a change in composition and a change in properties.

Chlorine is used to kill harmful organisms in swimming pools.

Sodium is stored under oil to keep it from reacting with oxygen or water vapor in the air. Sodium vapor produces the light in some street lamps.

Sodium Chloride (commonly known as table salt) is used to season or preserve food.

Distinguishing Substances and Mixtures

How can substances and mixtures be distinguished?

If the composition of a material is fixed, the material is a substance. If the composition of a material may vary, the material is a mixture.

▪ This flowchart summarizes the process for classifying matter.

Iron is abundant, easy to shape when heated, and relatively strong, especially when mixed with carbon in steel. Over time, objects made of iron will rust if they are left exposed to air. You will learn to recognize chemical changes and to distinguish them from physical changes.

Chemical Changes What always happens during a chemical change?

The ability of a substance to undergo a specific chemical change is called a chemical property.

Chemical properties can be used to identify a substance. But chemical properties can be observed only when a substance undergoes a chemical change.

During a chemical change, the composition of matter always changes.

Recall that during a physical change, the composition of matter never changes.

▪ A magnet separates iron from sulfur. This is an example of a physical change.

▪ A mixture of iron and sulfur is heated. The iron and sulfur react and form iron sulfide. This is an example of a chemical change.

A chemical change is also called a chemical reaction.

One or more substances change into one or more new substances during a chemical reaction.

A substance present at the start of the reaction is a reactant.

A substance produced in the reaction is a product.

Recognizing Chemical Changes

What are four possible clues that a chemical change has taken place?

Possible clues to chemical change include: a transfer of energy a change in color the production of a gas the formation of a precipitate.

▪ A precipitate is a solid that forms and settles out of a liquid mixture.

▪ Clues to chemical changes have practical applications.

Conservation of Mass

How are the mass of the reactants and the mass of the products of a chemical reaction related?

During any chemical reaction, the mass of the products is always equal to the mass of the reactants.

The law of conservation of mass states that in any physical change or chemical reaction, mass is conserved.

The conservation of mass is easily observed when a change occurs in a closed container.