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)