Learners read the definition of atomic weight and obtain the weights of elements by viewing the Periodic Table and charts that list atomic weights by name or symbol.

Learners observe that the melting of a solid and the freezing of its liquid occur at the same temperature. The melting point is an intrinsic property and is used to identify a substance.

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.

Learners study the effect that pressure has on boiling temperatures. Once a liquid has reached a full boil, additional heat does not raise the liquid’s temperature; however, pressure can vary the boiling point of a liquid. A brief quiz completes the activity.

Learners assign oxidation numbers to atoms in neutral compounds and in polyatomic ions. Six examples are worked through in detail, and three problems are provided.

Learners examine a table of common polyatomic ions. Eight examples are provided for practice.

Students use algebra to rearrange formulas and solve for the missing volume, density, or mass quantity.

Boyle's Law states that gas volume varies inversely with the pressure at constant temperature and is described by the equation PV = constant. An example of a sample of gas at two conditions of P and V is used to illustrate the law.

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.

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 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.

Learners identify combination, decomposition, displacement, and combustion types of redox reactions. They also watch a video clip that demonstrates the reaction of sodium and water.

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 interactive object, the learner practices identifying charges on ions.

Students solve a molarity problem in a drag and drop exercise.

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.

Learners examine the method used to calculate the mass percent of an element in a compound. Three examples and one problem illustrate the method.

Students read an explanation of chemical formulas in this animated activity. A quiz completes the object.

Learners examine the periodic table to identify metallic elements that have either fixed or variable oxidation states.

In this animated and interactive object, learners examine the inverse proportionality of wavelength and frequency and their relationship to the speed of light.

In this interactive object, learners calculate formula and molecular weights by working through five examples and two problems.

The definition of an isotope is illustrated using the three isotopes of carbon. The three isotopes of hydrogen are discussed as exceptions.

In this brief object, learners examine the direct relationship between the volume of a gas sample and the number of moles of gas. A problem is presented so students can test their knowledge of Avogadro's Law.

Learners view an animated presentation showing how the pH level of a cleaning solution is controlled in a closed-loop system in a manufacturing setting. A quiz completes the activity.