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.

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, learners examine the formation of peptide bonds through dehydration synthesis.

Learners examine a table containing the names of common cations and anions. They then check their knowledge by answering a series of questions.

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

Students identify the parts of a triple beam balance and practice measuring the mass of objects.

Students examine atomic structure and the octet rule.

Learners view an explanation of how to read a graduated cylinder by measuring the lowest portion of the meniscus. A quiz completes the activity.

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.

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

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

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

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

Roman numerals are used to identify the charges on metal cations having multiple oxidation states. Five examples are provided for practice.

Students read an introduction to the lab equipment used to contain and dispense chemicals. A quiz completes the activity.

Students read different definitions of "acids" and "bases." In an interactive exercise, they identify if a substance is an acid or a base.

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 solve a molarity problem in a drag and drop exercise.

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

Learners examine how melting, vaporization, and sublimation require energy input while freezing and condensation release energy.

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

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.

In this animated object, students examine what happens when electrons share molecules.

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

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.