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

The General Chemistry Virtual Textbook, or Chem 1, is broken into several sections covering various aspects of topics related to chemistry. This section deals with the shared-electron covalent bond and related topics such as the octet rule, electron-dot formulas, lone pair electrons, and more.

Introduction to drawing positions of electrons in Lewis Dot Structures. [14:42]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Explains what covalent bonds are and the difference between them and ionic bonds. Discusses the properties of polar and non-polar covalent bonds, and single and multiple covalent bonds, and gives analogies and examples of how covalent bonds work.

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Notes on covalent bonding, bond length, bond energies, Lewis dot structures, and percent ionic character. Colorful graphics.