WA.4. Physical Science
PS2. Matter: Properties and Change
6-8.PS2. Atoms and Molecules: In prior grades students learned the scientific meaning of the word matter, and about changes of state. In grades 6-8 students learn the basic concepts behind the atomic nature of matter. This includes the idea that elements are composed of a single kind of atom. Atoms chemically combine with each other or with atoms of other elements to form compounds. When substances are combined in physical mixtures, their chemical properties do not change; but when they combine chemically, the new product has different physical and chemical properties from any of the reacting substances. When substances interact in a closed system, the amount of mass does not change. Atomic theory also explains the ways that solids, liquids, and gases behave. These concepts about the nature of matter are fundamental to all sciences and technologies.
6-8.PS2A. Students know that substances have characteristic intrinsic properties such as density, solubility, boiling point, and melting point, all of which are independent of the amount of the sample.
6-8.PS2A.1. Students are expected to use characteristic intrinsic properties such as density, boiling point, and melting point to identify an unknown substance.
6-8.PS2C. Students know that all matter is made of atoms. Matter made of only one type of atom is called an element.
6-8.PS2C.1. Students are expected to explain that all matter is made of atoms, and give examples of common elements-substances composed of just one kind of atom.
PS3. Energy: Transfer, Transformation, and Conservation
6-8.PS3. Interactions of Energy and Matter: In prior grades students learned how heat, light, sound, and electrical energy are generated and can be transferred from place to place. In grades 6-8 students learn how energy and matter interact in various settings. Heat (thermal energy) always moves from a warmer to a cooler place through solids (by conduction) and through liquids and gases (mostly by convection or mechanical mixing). Light energy interacts with matter and with our eyes and allows us to see things. Electrical energy provides a convenient way to transfer energy to where and when the energy is needed. Sound is yet another form of energy produced by a vibrating object. These fundamental concepts of how matter and energy interact have broad application in all of the other sciences.
6-8.PS3A. Students know that energy exists in many forms which include: heat, light, chemical, electrical, motion of objects, and sound. Energy can be transformed from one form to another and transferred from one place to another.
6-8.PS3A.1. Students are expected to list different forms of energy (e.g., thermal, light, chemical, electrical, kinetic, and sound energy).
6-8.PS3A.2. Students are expected to describe ways in which energy is transformed from one form to another and transferred from one place to another (e.g., chemical to electrical energy in a battery, electrical to light energy in a bulb).