A comprehensive site focused on all of the Apollo missions. Includes details on launches and moon landings, with charts, statistics, and images. Especially interesting is the list of "Top Ten Apollo Results," which explains the major discoveries from the Apollo missions.

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Define matter and elements
Describe the interrelationship between protons, neutrons, and electrons
Compare the ways in which electrons can be donated or shared between atoms
Explain the ways in which naturally occurring elements combine to create molecules, cells, tissues, organ systems, and organisms

This site provides a detailed overview of atoms. Content explores an atom's structure, as well as what ions are, how atoms bond, what compounds are (including how to name compounds), and what isotopes are.

Here at Chem4Kids you can find some great information about the 4th element in the periodic table, "beryllium." Content focuses on beryllium's electrons, where you can find beryllium in nature, and how beryllium combines with other elements.

Here at Chem4Kids.com you can find some great information about the 5th element in the periodic table, "boron." Content focuses on boron's electrons, where you can find boron in nature and in the home, and how boron combines with other elements.

Here you can find lots of great information about helium. Learn about its electrons, where it exists in nature, and about the element itself!

Here you can find out about hydrogen, the first element in the periodic table. Content includes shell information, where to find it in nature, and why it is helpful to us.

This lesson introduces the concept of electricity by asking students to imagine what their life would be like without electricity. Two main forms of electricity, static and current, are introduced. Students learn that electrons can move between atoms, leaving atoms in a charged state.

This companion website of a NOVA program that aired in 1999 features extensive information that focuses on moon research and includes a history of the Apollo missions as well as the science of the moon's origins.

Explores electrons and their place in atoms.

A free CK-12 account is required to view all materials.

Covers energy levels of atoms, their relation to orbitals, and the significance of electrons at different energy levels.

A free CK-12 account is required to view all materials.

Practice using probability to describe the location of electrons in the atomic model. [3:25]

A basic explanation of spin and how it relates to electrons and quantum numbers.

In this animated video segment adapted from NASA, astronomer Doris Daou explains how the forces of speed and gravity keep the moon in a constant orbit around Earth. [1:36]