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Across 7. A fast moving electron given off by a nucleus. 8. Reactions involving the particles in the nucleus of an atom. 14. Made of two protons and two neutrons and is positively charged. 16. An example of a natural polymer. 19. The length of time needed for half of the atoms of a sample of a radioactive isotope to decay. 20. Atoms that form a straight line. 22. A radioactive isotope that can be followed through the steps of a chemical reaction or industrial process. 24. A clear or colored material that liquids can not penetrate. 25. Small molecules that are used to build a polymer. 27. Roofing tiles and bricks are made with this.

Down 1. A threadlike piece of glass or plastic. 2. Bright, satin finish that resists tarnish. 3. High energy waves, similar to X-rays. 4. The process determining the age of an object using the half-life of one or more radioactive isotopes. 5. The element that forms the bacbone of most polymers. 6. Atoms that form a chain with shoots off the sides. 9. A useful alloy of steel and tin. 10. A combination of two or more substances that creates a new material with different properties. 11. A large, complex molecule built from smaller molecules joined together in a repeating pattern. 12. The spontaneous emission of radiation by an unstable atomic nucleus. 13. A mixture made of two or more elements that has the properties of metal. 15. A flexible natural polymer found in fruits and vegetables. 17. A composite made from liquid plastic and glass fibers. 18. Synthetic polymers that can be molded or shaped. 21. A hard crystalline solid made by heating clay and other minerals materials. 23. Sand is heated to it's melting point to make this. 26. Atoms that form a circle.