• 6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
• 6-8: 4D/M1b. The atoms of any element are like other atoms of the same element, but are different from the atoms of other elements.
• 6-8: 4D/M1cd. Atoms may link together in well-defined molecules, or may be packed together in crystal patterns. Different arrangements of atoms into groups compose all substances and determine the characteristic properties of substances.
• 6-8: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they 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.
• 6-8: 4D/M6a. There are groups of elements that have similar properties, including highly reactive metals, less-reactive metals, highly reactive nonmetals (such as chlorine, fluorine, and oxygen), and some almost completely nonreactive gases (such as helium and neon).
• 6-8: 4D/M8. Most substances can exist as a solid, liquid, or gas depending on temperature.
• 6-8: 4D/M13. The idea of atoms explains chemical reactions: When substances interact to form new substances, the atoms that make up the molecules of the original substances combine in new ways.

• 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.

• 6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.

• 6-8: 12C/M3. Make accurate measurements of length, volume, weight, elapsed time, rates, and temperature by using appropriate devices.

This interactive animation explores models for the structure of water in three states: liquid, solid, and gas. It can be useful within a unit on preparatory chemistry or as a means to help students visualize what happens at the molecular level when matter changes state. The animations are designed to help students understand how temperature and the mutual attraction between molecules combined to determine the state.

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