• 6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.

• 4D (6-8) #1.  All matter is made up of atoms, which are far too small to see directly through a microscope. The atoms of any element are alike but are different from atoms of other elements. Atoms may stick together in well-defined molecules or may be packed together in large arrays. Different arrangements of atoms into groups compose all substances.
• 4D (6-8) #3.  Atoms and molecules are perpetually in motion. Increased temperature means greater average energy, so most substances expand when heated. In solids, the atoms are closely locked in position and can only vibrate. In liquids, the atoms or molecules have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.
• 4D (9-12) #1.  Atoms are made of a positive nucleus surrounded by negative electrons. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons.
• 4D (9-12) #2.  The nucleus, a tiny fraction of the volume of an atom, is composed of protons and neutrons, each almost two thousand times heavier than an electron. The number of positive protons in the nucleus determines what an atom's electron configuration can be and so defines the element. In a neutral atom, the number of electrons equals the number of protons. But an atom may acquire an unbalanced charge by gaining or losing electrons.

• 11B (6-8) #3.  Different models can be used to represent the same thing. What kind of a model to use and how complex it should be depends on its purpose. The usefulness of a model may be limited if it is too simple or if it is needlessly complicated. Choosing a useful model is one of the instances in which intuition and creativity come into play in science, mathematics, and engineering.

This animated tutorial does an solid job of helping beginners visualize the structure of an atom. They will explore the atomic nucleus, the electron cloud, ions, and isotopes. It gives students a good foundation to understand how electrons are shared to form molecules. **NOTE: Requires Shockwave to operate. Allow one class period in computer lab.

• Physical Sciences K-8 Matter and Interactions Unit
• Physics First Matter and Interactions Unit
• Conceptual Physics Matter and Interactions Unit

This tutorial introduces students to the basic structure of matter, including elements, molecules, and atoms. Animations help beginning learners visualize atomic/molecular structure and build a foundation to understand electron sharing. Editor's Note: The Shockwave tutorial takes one class period; the accompanying labs are optional.

• Physical Sciences K-8 The Standard Model Unit
• Physics First The Standard Model Unit
• Conceptual Physics The Standard Model Unit