DE.2. Materials and Their Properties
2.1. Properties and Structure of Materials
Enduring Understanding: The structures of materials determine their properties.
2.1.A. All matter consists of particles too small to be seen with the naked eye. The arrangement, motion, and interaction of these particles determine the three states of matter (solid, liquid, and gas). Particles in all three states are in constant motion. In the solid state, tightly packed particles have a limited range of motion. In the liquid state, particles are loosely packed and move past each other. In the gaseous state, particles are free to move. (Level: Essential)
DE.3. Energy and Its Effects
3.1. The Forms and Sources of Energy
Enduring Understanding: Energy takes many forms. These forms can be grouped into types of energy that are associated with the motion of mass (kinetic energy), and types of energy associated with the position of mass and with energy fields (potential energy).
3.1.D. Heat energy comes from the random motion of the particles in an object or substance. Temperature is a measure of the motion of the particles. The higher the temperature of the material, the greater the motion of the particles. (Level: Important)
3.3. Energy Interacting With Materials; the Transformation and Conservation of Energy
Enduring Understanding: Energy readily transforms from one form to another, but these transformations are not always reversible. The details of these transformations depend upon the initial form of the energy and the properties of the materials involved. Energy may transfer into or out of a system and it may change forms, but the total energy cannot change.
3.3.B. When a substance absorbs heat energy, or when a different form of energy is absorbed by the substance and is transformed into heat energy, the substance usually expands. The particles within the substance do not expand but the space between the particles increases. (Level: Essential)