Series: Chemistry Review

Rutherford Experiment rocks!

07/20/2009

~ brittanie

I really liked the way the professor explained the Rutherford Experiment. It helped a lot to understand how scientists discovered what made up an atom.

Below are the descriptions for each of the lessons included in the series:

• Chemistry: Creating the Periodic Table

  This lesson examines the creation of the Periodic Table of the Elements. Professor Harman walks you through the thought process involved in the grouping and the changes that led to the periodic table we are familiar with. Initially, many organization methods were tried, but Mendeleev's method was the most successful. The Mendeleev table used two characteristics for organizations, the atomic mass and the chemical reactivity. This method better organized the elements and made it possible to accurately predict unknown elements and their physical and chemical properties. Later discoveries changed the ordering of the periodic table. Ramsay discovered Argon, which doesn't have any chemical reactivity and whose mass fits in between two existing elements. This suggested a missing family that eventually came to be known as the Noble gases. Then, the discovery of the nucleus led to a change in ordering of atomic number (number of protons), instead of atomic mass. Using the atomic number better aligns the elements in their reactivity groupings.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Scientific (Exponential) Notation

  Scientific Notation is a shorthand method for expressing extremely large or small numbers. Prof. Yee uses Avogadro's number (6.022137 x 10^23) as an example of commonly used scientific notation. Scientific notation is a number that is expressed as r * 10^t, when r is a number greater than or equal to 1 and less than 10. The exponent will be positive if the actual number is greater than 1 and negative if the actual number is smaller than 1. Scientific notation is also a way to ensure that it is not ambiguous as to how many significant figures are in the number. Prof. Yee then instructs you how to add and subtract with numbers in scientific notation, first expressing both numbers to the same power of 10. Then he will teach you how to multiply and divide numbers in scientific notation. Finally, he will show you how to compute numbers in scientific notation with powers and roots.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Organic Nomenclature

  As with previous chemical naming conventions, organic chemistry has its own nomenclature. Organic compounds are compounds with carbon. Hydrocarbons are compounds that contain only hydrogen and carbon in varying amounts. These are broken into three groups, alkanes, alkenes, and alkynes. Alkanes have an -ane suffix. Similarly, alkenes have an -ene suffix and alkynes keep the -yne suffix. Professor Harman teaches you the standard prefixes that are used to indicate the number of carbon atoms that are in each of the compounds. These include meth-, eth-, pro-, but-, and pent-. These prefixes also pertain to alcohols. Alcohols have an OH group connected to a hydrocarbon and can be identified by an -ol suffix. Once you know some of the common prefixes and suffixes, it is easy to identify characteristics of larger, unknown compounds.

  This lesson is perfect for review for a CLEP test, mid-term, final, summer school, or personal growth!

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Examining Atomic Structure

  Professor Harman explains isotopes and atomic mass in this lesson covering atomic structure. Most elements exist in nature as more than one isotope. Isotopes are atoms that have the same number of protons as the element but a different number of neutrons. The number of protons always remains the same, as this number (also known as the atomic number) is what determines the element. Prof. Harman also introduces atomic mass units, or amu's, which are a more convenient unit for describing the very small masses of atoms. Next, Professor Harman explains more about the masses of elements. The amu is derived from carbon 12 and is equal to 1.6605 x 10^-27. The relative atomic mass listed on the periodic table of the elements is a weighted average of the masses of the isotopes of an element. You might also observe that the mass of an isotope is less than the sum of masses of its nucleons and electrons. Professor Harman explains the relationship between mass and energy that Einstein discovered, and binding energy.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: The Measurement of Matter

  Science involves a lot of measuring, but measurements are meaningless without units. Units, however, developed differently all over the world, and many are derived from parts of the body, such as the foot, the hand, and the cubit. Scientists developed a method of measurement for science that is more uniform, called the Systeme Internationale d'Unites (French for ""The International System of Units""), or the SI system. Professor Yee discusses the common measurements (such as length, mass, time, temperature) and their units (meter, kilogram, seconds, kelvins). In addition to the standard measurements, there are additional measurements that are derived from calculations using the standard measurements (energy, force, power). Many of these standard units are larger than most chemists will use, so Prof. Yee also gives us prefixes and some more derived units that are more commonly used for chemistry.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: The Concept of Equilibrium

  Professor Harman explains the concept of equilibrium. In a dynamic equilibrium, though appearing static at the acroscopic level, the forward reaction equals the reverse reaction. To create this type of equilibrium, the system must be closed. This can occur in a chemical system, as well. In chemical equilibrium, the forward and reverse reactions are equal and the concentrations of products and reactants do not change. Professor Harman also explains how you can determine the direction of equilibrium mathematically. To do this, you can look at the partial pressures. As the pressures level out, the system reaches equilibrium. You can also look at the rates of the forward and reverse reactions. When the rates become equal, the system has reached equilibrium. Then, Professor Harman explains that if the equilibrium is disrupted, a new equilibrium will establish in which the overall ratios pf products and reactants are equal. These ratios help to determine the Equilibrium Constant, which reveals the direction of the overall balance of the chemical system.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Early Discoveries and the Atom

  In this lesson, Professor Harman discusses early discoveries of the atom and the electron. Democritus first used the word ""atom"" meaning ""indivisible,"" but it was Dalton who furthered the concept. Dalton's 1808 Atomic Theory stated that 1) all matter is composed of atoms, which are indivisible, 2) elements consisted of only one type of atom and had 1 characteristic mass, 3) compounds consisted of 2 or more atoms, and 4) a chemical reaction is a rearrangement of the atoms. There are two problems with this original theory as atoms are divisible and elements can have more than one characteristic mass. The parts of the atom are the electron, the proton, and the neutron. J.J. Thompson won the Nobel Prize in 1906 for his discovery of electrons and their properties. Professor Harman will explain the cathode ray tube that J.J. Thompson used to determine the charge-to-mass ratios of electrons. He will also explain an oscilloscope, which helps to demonstrate this principle of electrons.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Naming Chemical Compounds

  Naming chemical compounds can be tricky, and requires a little bit of knowledge about the trends and naming conventions. First, Professor Harman explains that how you name a compound will depend on the type of compound - whether it is an ion, molecular compound, acid, or base. For ions, the way you name the ion will depend on whether the compound is a cation or anion and whether or not it is monatomic, polyatomic, or a transition metal. Anions follow slightly more difficult naming conventions. Molecular compounds use Greek prefixes and will always start with the element furthest from Fluorine. Some molecular compounds have common names (such as water), and these are always used. Bases are simply named like ionic materials. Acids are named based on the suffix of the anion they are derived from. If the anion ends in -ate, the acid uses an -ic suffix. If the anion ends in -ite, the acid uses an -ous suffix.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Understanding the Nucleus

  In this lesson, Professor Harman explains the discovery of the nucleus and Neutrons. The nucleus of atoms was discovered using radioactivity, which is the spontaneous emissions of particles of radiation fron an atom. Prof. Harman talks about early experiments with radioactivity, the discovery of gamma, alpha, and beta particles and their characteristics. Alpha particles were instrumental in the discovery of the nucleus of atoms. The Rutherford Gold Foil Experiment used alpha particles aimed at gold foil. The vast majority of the particles went through the gold foil, but approximately 1 in every 8000 was deflected at a severe angle. Rutherford hypothesized that this was only possible if the majority of the atom's mass was held in one central location, which he deemed the 'nucleus.' It was detemined that the nucleus of an atom is very small, analogous to one lightbulb, if Las Vegas is an atom. This discovery led to a revision of the ""Plum Pudding"" model of an atom to the ""Planetary"" model.

  Professor Harman also talks about the Chadwick experiment that discovered Neutrons. There was mass in an atom still unaccounted for by protons and electrons. Commonly used experiments could not discover it, though, since Neutrons are neutral and all the experiments used a charge. After discussing the Chadwick experiment using Beryllium, Professor Harman revisits Dalton's Atomic Theory.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: The Wave Nature of Light

  The study of quantum mechanics started around 1910. Professor Harman uses sugar as an example of the limits of measurment. You are ultimately limited to measuring sugar by the mass of the sugar molecule. Mass is quantized, meaning in comes in discrete quanta. A quantum is the smallest quantity or increment of something. Light, energy, and matter are all quantized. Light is quantized because it is actually a wave and behaves according to the properties of waves, which Professor Harman explains. The speed of light waves is fixed at 3.00 x 10^8 meters per second, however the frequency and wavelength can change and have an inverse relationship. The speed of light (c) is equal to the frequency times the wavelength. Light waves with different frequencies are percieved by our eye as different colors. Professor Harman explains that visible light is a very small part of the Electromagnetic Spectrum, the continuum of wavelengths. This spectrum also includes gamma rays, x-rays, ultra-violet light, infrared light, microwaves, and radio waves.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Precision and Accuracy

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Significant Figures

  Prof. Yee begins this lesson with an example of Niagara Falls to demonstrate the importance of significant figures. He discusses visiting the falls and reading how much water goes over the falls every second in the standard approximation and metric equivalent. The metric number was not rounded, and he explains why this is odd, given the circumstance. He also uses an example of Bill Gates' worth. Significant Figures are the digits in a number that are important to the amount of error and are not just placeholders. The amount of error or uncertainty in a measurement must always be taken into account. Prof. Yee discuses zeros as placeholders and 5 rules to determine when zeros are significant. You will also learn rules for rounding and how to determine the number of significant figures in an answer when adding, subtracting, multiplying, and dividing.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Understanding Electrons

  After J.J. Thomson's experiment to determine the charge to mass ratio for electrons, Robert Millikan devised an experiment to find the actual mass and charge of electrons. Robert Millikan won the Nobel Prize in 1923 for what is now known as The Millikan Oil Drop Experiment. In this experiment, Millikan atomized oil into small droplets in a box with two charged plates in it. The first plate had a small hole through which gravity would pull the droplets down. If and electric field was added to the plates, the neutral droplets would still fall through the hole. However, if the air between the plates is ionized, the electrons are removed from the air and attach to the oil droplets. The now negatively charged droplets are repelled from the positively charged bottom plate and can be made motionless with a proper balance of the coulomb force between the plates. With this information, and the known charge to mass ratio of an electron, Prof. Yee will show you how Millikan determined the charge (1.60 x 10^-19 Coulombs) and the mass (9.11 x 10^-31 kilograms) of an electron.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Balancing Chemical Equations

  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.

  This lesson is perfect for review for a CLEP test, mid-term, final, summer school, or personal growth!

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Describing Chemical Formulas

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: States of Matter

  Science is a method for categorizing the world around us. One way to do this is to categorize matter (anything that has mass and takes up space). Matter can be categorized by state (or phase) - whether it is a solid, a liquid, or a gas. A solid has a fixed shape and volume. A liqid has a fixed volume, but not shape. And a gas has neither a fixed volume or shape. In addition to its state, matter can be categorized as either pure or a mixture. Pure matter is made up of only one component. Pure substances are either elements, which are the fundamental building blocks of matter, or compunds, which are chemically bonded atoms. Mixtures are substances that can be separated by physical techniques and are either homogeneous or heterogeneous.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: The Nature of Energy

  Energy is the capacity to do work or transfer heat. Professor Yee introduces Thermochemistry, or the study of energy changes associated with a chemical system. He introduces Kinetic Energy (the energy associated with motion), Potential energy (which is stored energy), and internal energy (which is the sum of kinetic and potential energy). Internal energy is difficult to define in chemistry, as Potential energy is not always evident. However, in chemistry, often the change in energy is most important, and this can be defined as: (final energy - initial energy). Lastly, Professor Yee introduces two different units for measuring energy, Joules and Calories. Joules measure energy as work, with work being the energy that moves an object against a force. Work, in chemistry, is often PV work, or a gas expanding against external pressure. Calories measure heat, or the transfer of energy from one object to another by a change in temperature. 1 cal is equal to exactly 4.184 Joules, and is approximately 1/1000 of a food calorie.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Chemical Reactions & Equations Intro

  This introduction to stoichiometry discusses balanced chemical reactions. A chemical reaction is basically a recipe on the atomic level that instructs you how to create new molecules from existing ones. However, the law of the conservation of mass means that you must have the same number of atoms in the molecules that are created as in the molecules that reacted. A balanced chemical reaction is an expression of this law. Professor Yee shows you the different parts of a balanced reaction, including the stoichiometric coefficient, the reactants (on the left side of the reaction), the products (on the right side of the reaction), and the phase. To ensure a balanced equation, Professor Yee explains how to multiply the stoichiometric coefficient by the subscript to determine the number of atoms in the reactants and the products. He reminds you that no coefficient or subscript indicates either one molecule or one atom.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: The Heisenberg Uncertainty Principle

  Bohr's model predicted quantized energy levels and distances from the nucleus, but the Heisenberg Uncertainty Principle disproves this. Professor Harman suggests that we examine the way we locate things as an example of how the Heisenberg Uncertainty Principle works. We locate objects by detecting photons that are bounced off an object from a light source. In order to get better resolution, we want to use the smallest wavelength possible. However, the smaller the wavelength, the higher the energy of the photons. This is a problem if we are observing people, because we can actually cause harm to them. It is a problem when trying to observe electrons, because if we can find the location, the photon we must use has such a high energy that it will change the momentum of the electron. The Heisenberg Uncertainty Principle states that the error in momentum x the error in location must be greater than or equal to 5.27 x 10^-35 s. Thus, the smaller the object, the greater the uncertainty in knowing both its exact position and exact momentum. At the subatomic level, it is thus impossible.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: The Bohr Model

  If you pass sunlight through a prism, it appears that all the colors are present, but there are actually four frequencies that are missing, called the Fraunhofer spectrum. These are the same four frequencies that are visible in the hydrogen emission spectrum. In 1913, Bohr hypothesized that electrons are quantized and have orbits that are set distances from the nucleus of the atom, much like planets in orbit. Changes in energy between higher energy levels of electrons of hydrogen atoms exactly correspond to the lines in the visible region of the hydrogen emission spectrum. Professor Harman explains the mathematics behind determining these frequencies and the Rydberg constant. These provide the lines in the visible spectrum, what is known as the Balmer series, the frequencies in the Lyman series (ultra-violet), and the frequencies in the Paschen series (infrared). However, the Bohr model is incorrect in assuming that electrons have the characteristics of a particle and a fixed distance from the nucleus, and this model does not hold up for other elements.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: The First Law of Thermodynamics

  In this lesson, Professor Yee introduces thermodynamics. The First Law of Thermodynamics states that the total energy of the universe is constant. Remember from the lesson on the nature of energy that the universe is defined as the system + surroundings, and thus the First Law of Themodynamics correlates to chemical reactions. Another way to state this law is that the change in energy is equal to heat + work. Next, Professor Yee teaches us that the change in energy and energy itself are state functions. A state function is a property that is determined by the state of condition and not how the current state was reached. He explains this better using the concepts of altitude and distance. The altitude of a city is a state function because it is not dependent upon how you reach the city. The distance you drive to get to the city is not a state function because it will depend upon the route you take driving there.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: The Scientific Method

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."
  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: The Wave Nature of Matter

  Because of the Heisenberg Uncertainty Principle, we know that Bohr's theory about electrons is incorrect. In 1924, De Broglie postulated that electrons are quantized, but, like light, they have wave properties. He determined that wavelength = Planck's Constant/momentum. This means that if you have 2 particles with equal masses traveling at different speeds, the slower particle will have the longer wavelength. And if you have 2 particles with different masses traveling at the same speed, the smaller particle will have the longer wavelength. Professor Harman explains the mathematics behind this and discusses Angstroms. In 1927, Davisson and Germer proved that particles (specifically electrons) have wave properties. Professor Harman explains the constructive and destructive interfence properties of waves to explain their experiment using crystals. Lastly, Professor Harman uses a guitar to explain standing waves, which produce quantized prequencies. This helps to explain that, because electrons also have quantized frequencies, they can only be found in specific energy levels.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Dean Harman is a professor of chemistry at the University of Virginia, where he has been honored with several teaching awards. He heads Harman Research Group, which specializes in the novel organic transformations made possible by electron-rich metal centers such as Os(II), RE(I), AND W(0). He holds a Ph.D. from Stanford University.

• Chemistry: Dimensional Analysis

  In this lesson, you will learn how to convert measurements from one unit to another. You will learn how to create a conversion factor, which is always a factor of one that is constructed from a known quality. When creating a conversion factor, you will want to make sure to choose one that allows you to cancel out unwanted units. Prof. Yee also discusses significant figures when using conversion factors. Since conversion factors are considered exact, they have an infinite number of significant figures that are not limited. The data will limit the number of significant figures that you will use in an answer. Objects that are counted are also considered exact with unlimited significant figures. You will learn how to link multiple conversion factors, which is sometimes necessary when converting from one unit to another. Prof. Yee reminds you to make sure you always ""take the units along for the ride"" to ensure that you are finding your answer in the proper units. Finally, you will learn the proper conversion factors for converting both from degrees Farenheit to degrees Celsius and from degrees Celsius to degrees Kelvin.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.

• Chemistry: Properties of Matter

  The properties of matter are another way to categorize the world. Properties can be quantitative (described in terms of number and measurement) or qualitative (described in terms of appearance and not associated with a number). Matter has physical properties, which are properties that can be observed or measured without changing the chemical composition of matter. Some examples of physical properties include mass, volume, temperature, and phase. Physical properties are also either intensive, meaning the property is not dependent upon the amount of matter (like density, temperature, boiling point) or extensive, meaning the property is dependent upon the amount of matter (like weight and volume). To demonstrate these, Prof. Yee gives an example of density using different types of soda. He also uses candles to demonstrate physical and chemical changes. A physical change is a change to the form of the matter and not its composition. In contrast, a chemical change is a change of substance during a chemical reaction that changes the matter's chemical identity.

  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 http://www.thinkwell.com/student/product/chemistry. 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, biochemistry, organic chemistry, and more."

  Gordon Yee is an associate professor of chemistry at Virginia Tech in Blacksburg, VA. He received his Ph.D. from Stanford University and completed postdoctoral work at DuPont. A widely published author, Professor Yee studies molecule-based magnetism.