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 interactive, scaffolded activity allows students to build an atom within the framework of a newer orbital model. It opens with an explanation of why the Bohr model is incorrect and provides an analogy for understanding orbitals that is simple enough for grades 8-9. As the activity progresses, students build atoms and ions by adding or removing protons, electrons, and neutrons. As changes are made, the model displays the atomic number, net charge, and isotope symbol. Try the "Add an Electron" page to build electrons around a boron nucleus and see how electrons align from lower-to-higher energy. This item is part of the Concord Consortium, a nonprofit research and development organization dedicated to transforming education through technology. The Concord Consortium develops deeply digital learning innovations for science, mathematics, and engineering. The models are all freely accessible. Users may register for additional free access to capture data and store student work products.

In this interactive activity, learners build computer models of atoms by adding or removing electrons, protons, and neutrons. It presents the orbital model of an atom: a nucleus consisting of protons and neutrons with electrons surrounding it in regions of high probability called orbitals. Guided tasks are provided, such as constructing a lithium atom and a carbon-12 atom in the fewest possible steps. The activity concludes with a model for building a charged hydrogen atom (an ion). Within each task, students take snapshots of their work product and answer probative questions. This item is part of the Concord Consortium, a nonprofit research and development organization dedicated to transforming education through technology.

A complete, web-based, multi-media textbook covering a wide variety of Chemistry concepts.

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

An explanation of groups on the Periodic Table and their characteristics. [8:19]

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.

Test your electron-configuration skills in this animated exercise. Practice writing the abbreviated configurations for some of the common elements on the periodic table.

The Pauli Exclusion Principle requires that all electrons in an atom have unique energy levels.

Learn to identify different molecular shapes, to understand the interactions that create these shapes, and how to predict a molecule's shape given certain information about it. Explore these concepts using three-dimensional computer models and answer a series of questions to reinforce your understanding.

an explanation of the electron configuration of the transition metals on the Periodic Table. [5:33]

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.

An excellent tutorial that examines VSEPR and pairs of valence electrons. The valence shell electron pair repulsion concept is explored using animated models. Includes a VSEPR calculator. Use the toolbar on the left to navigate through the site.

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

A description of VSEPR with 3 electron clouds and various types of molecules. [12:33]

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.