www.mindbites.com In this lesson, you will learn the common nomenclature of chemistry. Professor Harman defines and contrasts atoms, molecules, ions, and ionic salts/covalent solids. Then Professor Harman covers written chemical formulas and visual representations of molecules. A molecular formula is a chemical formula that represents the actual number of atoms of each element within a molecule. An empirical formula is a chemical formula of a compound written with the smallest integer ratio of subscripts. Empirical formulas are always used to describe ionic compounds and covalent network solids. Various visual representations of molecules include the ball and stick three dimensional model that closely represents the structure of the molecule, a line drawing that approximates the structure in two dimensional terms, and a shorthand often used by organic chemists. Professor Harman warns that molecules are defined by their unique arrangements of atoms, and a formula can represent many different molecular compounds (known as isomers). Taught by Professor Harman, this lesson was selected from a broader, comprehensive course, Chemistry. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers atoms, molecules and ions, stoichiometry, reactions in aqueous solutions, gases, thermochemistry, Modern Atomic Theory, electron configurations, periodicity, chemical bonding, molecular geometry, bonding theory …
Chemistry: Describing Chemical Formulas
Chemistry: Balancing Chemical Equations
www.mindbites.com Professor Yee walks you through the process of determining a balanced equation from an unbalanced chemical equation using a method called Balancing by Inspection. There are no hard and fast rules for this method, but Prof. Yee gives you several tips and multiple examples. The first tip Prof. Yee gives you is to start with the molecule or compound that is the most chemically complex. If there is not one compound that stands out, he recommends beginning with the first chemical compound in the equation, as it is generally the one that is being reacted on. He recommends that you leave any pure elements for last. Due to convention, all of the coefficients in a balanced chemical equation must be whole numbers, so Professor Yee shows you how to adjust an equation by multiplying through by the least common multiple. Finally, he reminds you that the number of atoms of each element in the equation must be balanced both on the reactant side and the product side of the equation. Taught by Professor Yee, this lesson was selected from a broader, comprehensive course, Chemistry. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers atoms, molecules and ions, stoichiometry, reactions in aqueous solutions, gases, thermochemistry, Modern Atomic Theory, electron configurations, periodicity, chemical bonding, molecular geometry, bonding theory, oxidation-reduction reactions, condensed phases …
Chemistry: The Scientific Method
www.mindbites.com This lesson uses a simple experiment of burning different substances to help explain the Scientific Method and to associate the process to the Scientific Hierarchy, the formulation of the Law of Conservation, and the beginning of modern chemistry. The Scientific Method is the process used to organize and test the observations about the world that are made during experimentation. This method starts with observation and experimentation. Then, patterns, trends, and laws are found in the observations. These help us to formulate hypotheses, which either lead to the formulation of theories or further experimentation and observation. Often, hypotheses will need to be revised, when newer observations conflict. The Scientific Method has led to a Scientific hierarchy of laws, hypotheses, and theories, which are defined in this lesson. This process also led to the birth of modern chemistry, when Dalton formulated the 5 Atomic Theory Postulates from Lavoisier’s Law of the Conservation of Matter. Taught by Professor Gordon Yee, this lesson was selected from a broader, comprehensive course, Chemistry. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers atoms, molecules and ions, stoichiometry, reactions in aqueous solutions, gases, thermochemistry, Modern Atomic Theory, electron configurations, periodicity, chemical bonding, molecular geometry, bonding theory, oxidation-reduction reactions …
Chemistry: Precision and Accuracy
www.mindbites.com In this lesson, Prof. Yee discusses precision and accuracy in measurements. He explains that all measurements will have a degree of uncertainty due to instrumentation, and the range of uncertainty will appear in the last digit of the measurement. You want to have measurements that are both precise and accurate. Precision is the reproducibility of the measurement of a quantity and is tied to the concept of random error. Prof. Yee uses a ruler as an example of precision. Accuracy refers to how close a measurement is to a hypothetical true value. It is possible for a measurement to be precise but not accurate if there is a systematic error. Systematic error is an error inherent to the measurement of a value, such as a clock that is consistently 5 minutes fast. Finally, Prof. Yee explains the relationship between precision and accuracy using a game of darts. Taught by Professor Yee, this lesson was selected from a broader, comprehensive course, Chemistry. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers atoms, molecules and ions, stoichiometry, reactions in aqueous solutions, gases, thermochemistry, Modern Atomic Theory, electron configurations, periodicity, chemical bonding, molecular geometry, bonding theory, oxidation-reduction reactions, condensed phases, solution properties, kinetics, acids and bases, organic reactions, thermodynamics, nuclear chemistry, metals, nonmetals …