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 complete an exercise to match chemical formulas with the names of binary compounds, tertiary compounds, and ions.

In this well-illustrated object, learners examine basic floral anatomy. The flower is the reproductive organ of the angiosperm.

In this screencast, learners categorize different metabolic activities as catabolic or anabolic and follow a glucose molecule through the processes of glycolysis, aerobic respiration, and fermentation.

In an interactive exercise, learners identify the human body sites that harbor a normal resident flora and the sites that are sterile.

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

In this animated object, learners examine the chemistry behind table salt.

In this highly interactive object, learners associate basic line types and terms with engineering drawing geometry. A quiz completes the 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.

In this animated and interactive object, learners examine the basic parts and the linear movement of a hydraulic cylinder. 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.

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

In this animated and interactive object, learners identify the valves and chambers of the heart.

Explore what passive transport osmosis is and how it moves water through a semipermeable membrane.

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

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.