General Chemistry CHEM 1103 Summer, 2003

1. General ChemistryCHEM 1103Summer, 2003 Nicholas H. Snow Department of Chemistry and Biochemistry Seton Hall University

2. Course Structure • MTR meetings 0815-1110 • lectures • Discussion/problems • Quizzes (0815 Thursdays) • MTR Meetings 1130-1430 • Laboratory • Laboratory meets in McNulty 321

3. Course Structure, con’t • Four quizzes- 100 points each • short answer, long answer • Laboratory - 400 points • Final - 200 points • final will be multiple choice first semester ACS examination

4. Study recommendations • Study chemistry a few hours everyday; cramming does not work! • Study ahead, so that you know what is coming • Ask Matt, Rafael and me questions! • You should not have to study for the tests if you have properly prepared

5. Chapter 1 - What is Chemistry? • Science is the attempt to organize and study nature • Chemists are interested in all matter • Includes problems in material science and biochemistry • micro- and nanoelectronics • medicine • green chemistry • In particular • properties of matter • transformations of matter • interactions of different types of matter

6. Experimentation • How we learn about matter and nature • Chemistry can advance by: • deliberately planned courses of experimentation • accidental discoveries • Our experimentation and interpretation must be designed to be prepared for both possibilities • Experimentation can also be driven by improvements in methodology and technology (better equipment and methods)

7. Scientific method • Hypothesis - initial idea about what matter will do • Experiment - test of the hypothesis • Theory - an explanation of what was observed • Laws - statements summarizing observations (not explanations)

8. Structure of matter • Properties of matter • macroscopic (can be seen with the eye) • microscopic (underlying structure) • Composition of matter • atoms - basic unit of matter • molecules - combinations of atoms • There are a little over 100 types of atoms, but only about 20 are commonly encountered

9. Chemicals • Elements - types of atoms • Compounds - substances composed of two or more different atoms in a definite proportion by mass • Chemical formulas • indicate the atoms in the compound • number of each atom in the compound is designated by subscripts

10. Periodic Table • Elements demonstrated properties that repeated in a cyclical or periodic fashion • Properties included both physical and chemical • Gross organization of periodic table • metals • metalloids • nonmetals

11. Periodic Table • Metals • good conductors of heat, electricity • shiny, malleable, ductile • all solids except Hg • Nonmetals • properties are highly variable, but are generally poor conductors • can be brittle solids, gases or liquids • Metalloids • often called semiconductors • dull, brittle solids

12. Families • Rows are called periods • Columns are called families • alkali metals • alkaline earths • noble gases • halogens • chalcogens • pnicnogens

13. Characteristics of matter • Elements - matter that cannot be broken down into simpler substances by chemical means • Compounds - combinations of two or more different elements in definite proportion by mass • Mixtures - combinations of matter that can be separated by physical means

14. Phases of matter • gas - particles of matter not in constant contact and are constantly moving • does not have a specific shape • does not have a specific volume • liquid - particles are in constant contact, but are still in constant motion • has a specific volume • does not a definite shape • Solid - particles are in contact and cannot move through the material • has a specific volume and shape

15. Mixtures • homogenous - same throughout down to the molecular level; often called a solution • heterogeneous - contains regions or phases of different matter; especially at the macroscopic level

16. Physical properties • can be measured without changing the substance • those typically measured • volume • mass • time • temperature

17. Measurement • Scientific notation (do you know how to use your calculator?) • Units • prefixes (memorize them) • SI and common metric units • Dimensional analysis • Precision - exactness of a measurement • Accuracy - how close a measurement is to the “true” value

18. Significant Figures • number of digits expressed in a numerical value • all nonzero digits are significant • imbedded zeroes are significant • zeroes used to hold place are generally not significant • 12,000 - hard to say • 0.0012 - zeroes here are not significant

19. Calculations • Physical properties are often measured that must be incorporated in calculations to yield chemically significant information • Density is a good example:

20. Properties • Extensive properties are those that depend on the amount of a substance • mass and volume • Intensive properties depend on the material and are independent of the amount of material • density is a good example

21. Precision in calculations • Scientific measurements often require several measurements from more than one instruments • This data is then used to calculate a quantity of interest • For example, to measure density, one must measure mass and volume using two separate instruments

22. Precision of calculations • When adding or subtracting, the number of decimal places in the result is the number of decimal places in the number with the fewest places • When multiplying or dividing, the number of significant figures in the result is the same as in the quantity with the fewest significant figures • Postpone adjusting the result to the correct number of significant figures until the calculation is complete • Remember, the calculator always gives you too many significant figures.