Why do we study science? What is science? • Sciencecomes from the Latin word scire, which means, “to know.” • We study science in order to understand the world around us. • Chemistry is often called the central science as so many naturally occurring phenomena involve chemical change.
Chemistry, itself, can be further categorized • 1. Analytical chemistry • 2. Organic chemistry • 3. Inorganic chemistry • 4. Physical chemistry • 5. Biochemistry • 6. Nuclear chemistry
Evolution of Chemistry • In a recent survey by American Chemical Society, entering college students were asked to express their attitudes about science courses. • Chemistry was rated as the most relevant science course. • 64% rated chemistry as highly relevant to their daily lives. • Unfortunately, 83% thought chemistry was a difficult subject.
The earliest concept of science began with the ancient Chinese, Egyptian, and Greek civilizations. • The Chinese believed the universe was created by the interaction between two forces, Yin and Yang, and were responsible for everything in nature. • 600 B.C. The Greeks • Science was pure reasoning. • The universe consisted of a single element. • Thales, founder of Greek science, thought that water was the single element. • Earth is a flat disc floating on a universe of water. • Air and Space were less dense forms of water and the Earth more dense.
350 B.C. Aristotle, Greek • Air, earth, water, and fire were basic elements. • Aristotle’s influence was so great that this theory dominated our understanding for nearly 2000 years. Fire Hot Dry Air Earth Ashes: earth Dried Wood: fire, earth Moist Cold Tree: fire, water, earth Water
Destruction of the Greek civilization, European science fell and did not reappear until the Middle Ages. • Eighth century A.D., Arabs • Introduce the pseudoscience of alchemy. • Alchemists looked for the magical elixir that had miraculous healing powers and could transmute base metals into gold. • Led to planned, systematic, scientific procedures and laboratory apparatus. • Mainly worked by trial and error.
Recipe for the Philosopher’s Stone: • Take all the mineral salts there are, also all salts of animal and vegetable origin. Add all the metals and minerals, omitting none. Take two parts of the salts and grate in one part of the metals and minerals. Melt this in a crucible, forming a mass that reflects the essence of the world in all its colors. Pulverize this and pour vinegar over it. Pour off the red liquid into English wine bottles, filling them half-full. Seal them with the bladder of an ox (not that of a pig). Punch a hole in the top with a coarse needle. Put the bottles in hot sand for three months. Vapor will escape through the hole in the top, leaving a red powder…
During the 1200’s, Robert Bacon, English • Gain an understanding of the natural world through observations and experimentation rather than pure logic. • 1661 Robert Boyle, English • Published The ScepticalChymist • Stated that scientific speculation was worthless unless it was supported by experimental evidence. • Led to the scientific method. • Late 1700’s Antoine Lavoisier, French • Organized chemistry into a comprehensible science. • Transformed chemistry from a science of observation to the science of measurement that it is today. • Organized a magnificent laboratory where scientists like Benjamin Franklin and Thomas Jefferson visited. • Considered to be the founder of modern chemistry.
The Scientific Method • systematic approach to problem solving. • differs depending on what you are studying but there are a few basic steps. • State the problem. • Gather information on the problem. • Form a hypothesis. • Perform experiments to test the hypothesis. • Record and analyze data. • State a conclusion. • Repeat the work.
STATE THE PROBLEM: • What are you trying to find out? • GATHER INFORMATION ON THE PROBLEM: • Collect observations. • FORM A HYPOTHESIS: • Proposed solution, a tentative explanation • Educated guess, • PERFORM EXPERIMENTS TO TEST THE HYPOTHESIS: • Carefully devised plans and procedures.
In experiments there are factors that remain the same and there are factors that change… The constant and the variable……. • Constant(s) remain unchanged throughout the experiment. • The variable is the factor being tested. It changes or varies during an experiment. • There are two types of variables: • the dependent and the independent. • The independent variable is the variable that the experimenter physically changes. • (Only change one at a time!!!!) • The dependent variable changes because the independent variable changed. It DEPENDS on the independent variable. • The control is the dependent variable, not influenced by the independent variable. Conducting the experiment without the independent variable, gives you a starting point for an experiment, and shows the need for the independent variable.
Vertical axis Horizontal Axis • RECORDING AND ANALYZING DATA: • Record observations and measurements (aka DATA) • Usually written in a table. • A Visual representation of the data is called a GRAPH. • The x-axis (horizontal axis, left-to-right axis) represents the independent variable. • The y-axis (vertical axis, up-and-down axis) represents the dependent variable.
STATE A CONCLUSION: • Is there a pattern? Can you make a theory? • A theory gives a universally accepted explanation of the problem. Of course theories should be constantly challenged and may be refined as and when new data comes to light. • Theories are different to laws. A law is a summary of observed (measurable) behavior, whereas a theory is an explanation of behavior. A law tells what happens; a theory (model) is our attempt to explain why it happens. Laws state what general behavior is observed to occur naturally. • For example, the law of conservation of mass exists since it has been consistently observed that during all chemical changes the overall mass of the substances involved remains unchanged. • REPEAT THE WORK: • Check to see if the data is correct.