Vapor pressure is the pressure exerted by molecules in the gas phase in equilibrium with a liquid or a solid. Two examples are used to illustrate vapor pressure: the drying of clothes and the evaporation of ice.

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

In this screencast, we review the positions of metals, metalloids, and nonmetals in the Periodic Table and the general characteristics of each.

Students review the positions of metals, metalloids, and nonmetals in the Periodic Table and the general characteristics of each. A quiz completes the object.

In this animated and interactive object, learners examine the properties of liquids, solids, and gases.

In this animated and interactive object, learners examine the properties of liquids, solids, and gases.

Students examine atomic structure and the octet rule.

Students examine atomic structure and the octet rule.

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.

Learners examine how chemists use moles to "count" atoms by weight. Examples are given.

In this interactive object, learners determine the limiting reagent and the excess reagent in chemical reactions. Learners test their knowledge by solving three problems.

In this interactive object, learners determine the limiting reagent and the excess reagent in chemical reactions. Learners test their knowledge by solving three problems.

In this animated activity, learners examine what gases are composed of and how their particles interact. They also consider several assumptions that form the basis for the Kinetic Theory of Gases.

In this animated object, learners examine the formation of ester bonds in the synthesis of lipids using triglyceride biosynthesis as an example. Ester bond formation is described as a dehydration synthesis reaction.

Learners examine how vapor pressure is calculated. The vapor pressure of a liquid increases with increasing temperature. If the heat of vaporization and the vapor pressure at one temperature are known, the vapor pressure at a second temperature can be calculated.

Learners combine Boyle's Law and Charles's Law to solve for the pressure, volume, and temperature of a gas sample under two sets of conditions.

Students read brief descriptions of atoms, molecules, elements, and compounds, and complete a matching exercise that pictures these particles and molecules as pieces of taffy.

Students read brief descriptions of atoms, molecules, elements, and compounds, and complete a matching exercise that pictures these particles and molecules as pieces of taffy.

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

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

Learners observe that the volume of one mole of any gas is 22.4 L at standard temperature and pressure. An illustration shows that only the mass of the molar volume differs with the identity of the gas.

Learners view movie clips to determine the solubility of two ionic compounds. They also examine a solubility chart and predict the solubility of compounds.

Learners examine how five or six groups of electrons around a central atom cause the shape of the molecule to be trigonal bipyramidal, seesaw, T-shaped, linear, octahedral, square pyramidal, or square planar. Seven examples and three interactive questions are provided in this animated activity.

In this animated and interactive object, learners observe how two, three, or four groups of electrons around the central atom cause the shape of the molecule to be linear, trigonal planar, bent, tetrahedral, or pyramidal. Seven examples and eight interactive questions are provided.

In this animated and interactive object, learners observe how two, three, or four groups of electrons around the central atom cause the shape of the molecule to be linear, trigonal planar, bent, tetrahedral, or pyramidal. Seven examples and eight interactive questions are provided.