CHEM 3070 Fall 2006 Chad Stessman. Chapter 1 Chemistry is a Science- two components Technological-...
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Transcript of CHEM 3070 Fall 2006 Chad Stessman. Chapter 1 Chemistry is a Science- two components Technological-...
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 systemStarted with ancient Greeks 2500 years ago
Chemistry• Chemistry is a branch of science that
investigates how matter interacts with other matter.
• Roots in alchemy (500-1500 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)