In this animated and interactive object, learners follow two rules to write unit conversion fractions.

Learners convert units used to designate pressure. Units for pressure are atm, mm Hg, torr, and pascal.

Learners examine phase diagrams that show the phases of solid, liquid, and gas as well as the triple point and critical point.

Learners examine graphs and read that the heat of fusion is the heat energy absorbed by one mole of solid as it is converted to liquid, while the heat of vaporization is the heat energy absorbed by one mole of liquid as it is converted to gas.

In this interactive object, learners calculate the amount of heat evolved or absorbed in chemical reactions. Four practice problems are provided.

In this well-illustrated activity, learners examine the three types of intermolecular forces: dipole-dipole forces, London or Van der Waals forces, and the hydrogen bond. Two interactive questions are included.

Students examine standard pressure in this interactive object.

Learners use the coefficients in a balanced equation to develop the mole ratios of reactants and products involved in the reaction. Five interactive examples illustrate the method, and students test their knowledge by working four problems.

Learners examine the method for calculating the atomic weight of copper from the natural percent composition of each of its two isotopes.

In this screencast, students read about the basic organization and structure of the periodic table of elements. Students identify elements as belonging to a group, a period, or neither.

In this interactive and animated object, students distribute the valence electrons in simple covalent molecules with one central atom. Six rules are followed to show the bonding and nonbonding electrons in Lewis dot structures. The process is well illustrated with eight worked examples and two interactive practice problems.

Learners view several movie clips that demonstrate the use of an indicator to follow the neutralization reaction that occurs when an acid and a base are mixed. Students test their knowledge in a series of questions. Immediate feedback is given.

Students practice identifying common elements from the periodic table by name or symbol.

Learners read definitions of atomic symbols, atomic numbers, and mass numbers and then answer questions about the number of neutrons, protons, and electrons in select elements.

In this animated activity, learners examine the terms "half-reaction," "oxidizing agent," and "reducing agent" and follow five interactive examples to balance equations for oxidation-reduction reactions. Three problems are provided as a self-check.

In this interactive lesson, students examine the quantitative relationship between chemicals in a balanced mathematical equation.

In this well-illustrated object, learners examine the structures and properties of the four types of solids: molecular, metallic, ionic, and covalent network. Five interactive questions are provided.

In this animated activity, learners compare the van der Waals equation with the Ideal Gas Law.

Atomic weights are used to convert the mass of a sample into the number of moles of the element in the sample and vice versa. Four examples are provided for practice.

In this animated object, students examine the role that the solubility of water plays in various biological functions.

In this colorful, interactive object, learners examine how materials on the nanoscale compare with those on the macroscale. The focus is on the difference between macroscale and nanoscale gold in both color and melting point.

Learners view illustrations showing the direct dependence of the volume of a gas on temperature and consider the relationship between the Kelvin and Celsius temperature scales.

Ions are electrically charged particles obtained from an atom or from a chemically bonded group of atoms by adding or removing electrons. Eight examples illustrate the number of protons, neutrons, and electrons in positive ions (cations) and in negative ions (anions).

Learners examine how the boiling point increases with increasing pressure. An example from industry is given.

Students examine atomic structure and the octet rule.