General Chemistry CHEM 1103 Summer, 2003 Nicholas H. Snow Department of Chemistry and Biochemistry Seton Hall University Dr. W. R. Murphy, SHU

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

Course Structure, con’t CHEM 1107 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 Dr. W. R. Murphy, SHU

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

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

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)

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)

Structure of matter Properties of matter Composition 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

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

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

Periodic Table Metals Nonmetals Metalloids 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

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

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

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

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

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

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

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

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

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

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

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.