“Introduction to Chemistry”

Chemistry is the study of the composition, structure, and properties of matter and the changes it undergoes – such as burning fuels. C2H5OH + 3 O2  2 CO2 + 3 H2O + Energy Reactants  Products

5 Major Areas of Chemistry Analytical Chemistry- concerned with the composition of substances. Inorganic Chemistry- primarily deals with substances without carbon Organic Chemistry- essentially all substances containing carbon

Biochemistry- Chemistry of living things Physical Chemistry- describes the behavior of chemicals Boundaries not firm – they overlap and interact

What is Chemistry? Pure chemistry- gathers knowledge for the sake of knowledge Applied Chemistry- is using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing – leads to an application

Alchemy – developed the tools and techniques for working with chemicals The word chemistry comes from alchemy – practiced in China and India since 400 B.C.

SO……How do we use Chemistry to get answers?

The Scientific Method A logical approach to solving problems or answering questions.

Steps in the Scientific Method 1. Observations (uses your senses) a) quantitative involves numbers = 95oF b) qualitative is word description = hot 2. Formulating hypotheses (ideas) - possible explanation for the observation, or “educated” guess 3. Performing experiments (the test) - gathers new information to help decide whether the hypothesis is valid

Scientific Method “controlled” experiment- designed to test the hypothesis only two possible answers: hypothesis is right hypothesis is wrong We gather data and observations by doing the experiment Modify hypothesis - repeat the cycle

Scientific Method We deal with variables, or factors that can change. Two types: 1) Manipulated variable (or independent variable) is the one that we change 2) Responding variable (or dependent variable) is the one observed during the experiment For results to be accepted, the experiment needs to always produce the same result

3) Constant(s) – Conditions held constant throughout an experiment so that the IV can be isolated. Must always have! 4)Control – standard for comparison in an experiment. DO NOT always have to have!

Outcomes over the long term… Theory (Model) - A set of well-tested hypotheses that give an overall explanation of some natural phenomenon – not able to be proven Natural Law (or Scientific Law) - The same observation applies to many different systems; summarizes results - an example would be: the Law of Conservation of Mass

Law vs. Theory A law summarizes what has happened. A theory (model) is an attempt to explain why it happened – this changes as new information is gathered.

Collaboration / Communication When scientists share ideas by collaboration and communication, they increase the likelihood of a successful outcome Publishing research (ex. journals) International meetings/conferences