Introduction to Chemistry Chapter 1 Introduction to Chemistry

What is Chemistry? Chemistry: the study of matter and the changes that it undergoes Matter: anything that has mass and takes up space Mass: a measurement that reflects the amount of matter Weight: a measurement for the amount of matter and the effect of the Earth’s gravitational pull on that matter **Because living and nonliving things are made of matter, chemistry affects all aspects of lift and most natural events

Branches of Chemistry Organic Chemistry: most carbon containing chemicals Ex. Pharmaceuticals, plastics Inorganic Chemistry: in general, matter that doesn’t have carbon Ex. Minerals, metals & nonmetals, semi-conductors Physical Chemistry: the behavior and changes of matter and the related energy changes Ex. Reaction rates, reaction mechanisms Analytical Chemistry: Components and composition of substances Ex. Food nutrients, quality control Biochemistry: Matter and processes of living organisms Ex. Metabolism, fermentation

Technology: the practical use of scientific information Pure Research: seeks to grain knowledge for the sake of knowledge itself Applied Research: research undertaken to solve a specific problem or goal Technology: the practical use of scientific information Collaboration: a key to being successful in science When scientists collaborate and communicate, they increase the likelihood of a successful outcome

Scientific Method Scientific Method: a systematic approach used in scientific study **Question or Problem Observation: existing knowledge Qualitative Data: information that describes color, odor, shape, and other physical characteristics Quantitative Data: numerical information Hypothesis: a tentative explanation for what has been observed, and that can be tested Experiment: a set of controlled observation that test the hypothesis Independent Variable: in an experiment, that variable the experimenter plans to change Dependent Variable: in an experiment, the variable whose value depends on the independent variable Control: in an experiment, the standard that is used for comparison Conclusion: a judgement based on the information obtained Theory: is an explanation that has been supported by many, many experiments Scientific Law: describes a relationship in nature that is supported by many experiments (doesn’t try to explain)

Scientific Theory vs. Law Scientific Theory: explains a large number of facts and hypothesis Has withstood much testing Is synonymous to fact Plate tectonics is a theory built of many hypotheses of plate motion Scientific Law: describes a relationship in nature that is supported by many experiments Law of Gravity Newton’s Laws of Motion

A scientific inquiry Step One: Collection or Observations Dinosaurs extinct @ ~65 Ma Many other organisms extinct @ ~65 Ma Iridium (Ir) present at extinction Iridium (a metal) is found in meteorites, comets, certain lavas, and cosmic dust. Not normally found in high concentration at Earth’s surface

A Scientific Inquiry Step Two: Hypothesis development Testable? Comet or asteroid impact created the iridium anomaly Testable? Side effects? Dust cloud Fireball “Nuclear” winter Instant death

A Scientific Inquiry Step Three: Observations and Experiments Test for iridium world-wide Test for abrupt end to dinosaurs and plankton Crater?

A Scientific Inquiry Steps Four & Five: Accept, modify, reject? Iridium is world-wide Almost abrupt end to dinosaurs and plankton Later crater & soot found (Mexico's Yucatan Peninsula)