Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Static Electricity

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Static electricity can be produced by rubbing together two objects made of different materials. Electrons move from the surface of one object to the surface of the other if the second material holds onto its electrons more strongly than the first does. The object that gains electrons becomes negatively charged, since it now has more electrons than protons. The object that gives up electrons becomes positively charged. For example, if a nylon comb is run through clean, dry hair, some of the electrons on the hair are transferred to the comb. The comb becomes negatively charged and the hair becomes positively charged. The following materials are named in decreasing order of their ability to hold electrons: rubber, silk, glass, flannel, and fur (or hair). If any two of these materials are rubbed together, the material earlier in the list becomes negative, and the material later in the list becomes positive. The materials should be clean and dry.

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