CHEM 3070 Fall 2006 Chad Stessman

Chapter 1 Chemistry is a Science- two components Technological- facts, knowing how to do things.

Philosophical- theoretical, why do things happen. What might happen with an unknown system Started with ancient Greeks 2500 years ago

Chemistry Chemistry is a branch of science that investigates how matter interacts with other matter. Roots in alchemy ( AD) attempts to convert cheaper metals to gold.

Scientific Method Observations- accumulation of knowledge about the natural world Must be reproducible and observable by others

Develop a hypothesis-educated guess, to explain the observation. Design an experiment to test the hypothesis.

Develop a hypothesis-educated guess, to explain the observation. Design an experiment to test the hypothesis. Baa

Develop a hypothesis-educated guess, to explain the observation. Design an experiment to test the hypothesis. Baa

Must be a testable property or idea. If the test rejects the hypothesis a new hypothesis is developed. This new hypothesis is then tested If experiment is verifies the hypothesis then it is repeated.

Theories Eventually after enough verifying a hypothesis becomes a theory Theory-best explanation of various phenomena as of today. Always tentative, could be discarded or modified if new evidence is discovered. Theories can be used to predict behavior.

Law Large amounts of scientific data can be summarized in a brief statement, Law Universal under the stated conditions.

Newton’s Laws of Motion Objects in motion tend to stay in motion unless an external force is applied to it. Force equal mass times acceleration F=ma

Model Scientists use simple, maybe common examples to explain complicated systems. Models have limitations, and at some point diverge from the systems they are models for.

Limitations on Science Limited by the number of variables Must hold all but one variable constant With more advanced systems this becomes more and more difficult. Math, physics, chemistry, biology, social sciences

Risks vs. Benefits Every technology has certain risks, and benefits Benefits-advantages to certain technology Risks- hazards that lead to loss or injury

Desirability Quotient A way to determine the desirability of a certain technology DQ= benefits/risks Positive number good, negative bad

Pasteurized Milk Benefits-safe, clean and nutritious, a source of calcium Risks-some people are lactose intolerant DQ = High benefit/low risk

Thalidomide Drug used in 1958 to reduce morning sickness (benefit) Found to cause birth defects (risk) DQ(thalidomide) low benefit/ high risk

Other examples Lead paint Aspirin Space program

Chemistry’s Central Role Chemistry is central to most sciences Biology, agricultural sciences, medicine, communications, geology, etc.

Chemistry Research Broken into two areas Applied research- trying to find solutions to specific problems. Find new drugs, finding new plastics Basic Research-investigation for knowledge’s sake.

Chemistry-study of matter Matter-stuff that makes up all things, it has a mass. Mass- measure of the quantity of matter contained in an object. Greater mass the harder it is to change motion. Mass is the same anywhere in the universe

Weight Weight differs from Mass Weight is a measure of force Weight=mass x acceleration due to gravity

Physical vs. Chemical Properties Physical Property- physical characteristic and behavior. Color, odor, hardness Chemical Property- how a material interacts with other types of matter

Physical vs. Chemical Changes Physical Change- a change that does not entail a change in the chemical composition. Ex. melting point, boiling point Chemical change- involves a chemical change in the matter. Ex. burning, rusting

States of Matter Three common states of matter Solid, liquid and gas

Solid Maintains its ordinary shape and volume regardless of location. Ex. ice, gold bar, coins

Liquid Occupies a definite volume but assumes the shape of its container. Ex. water, ethanol, gasoline

Gas Maintains neither shape nor volume. It expands to fill the container it is in. Can be compressed. Ex. steam, oxygen, air

Substance and Mixture Substance- has a definite or fixed composition that does not vary sample to sample. Ex. pure water, 24-carat gold, 200- proof ethanol Mixture-composition is variable. Ex. salt water, 14-carat gold, air

Elements and compounds Substances are either elements or compounds Elements-fundamental substances of which all matter is composed. Ex. gold, oxygen, nitrogen Compounds-substances made up of two or more elements chemically combined. Ex water, ethanol

Elements Currently 115 substance which can not be broken down into simpler substances by chemical means. Carbon, oxygen, helium, iron, often refered to by shorthand notation, derived from first to letters of Latin name.

Atoms and molecules Atom- smallest characteristic part of an element Molecule- a group of atoms bonded together as a unit. Each molecule is the basic component of a compound

Measure of Matter To do scientific work we need accurate measurements of quantities of mass, volume, temperature, time ….. Since 1960 International System of Units, SI system has been used by scientists.

SI system has seven basis units Length-meter (m) Mass- kilogram (kg) Time- second (s) Temperature- Kelvin (K) Amount- mole (mol) Electric current- ampere (A) Luminous intensity- candela (cd)