Chemistry Crossword

3. pure substance that cannot be broken down into other substances; substance made up of only one type of atom
8. shiny, malleable, ductile element that conducts electricity
10. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
11. group 18 elements in the periodic table;the most stable and unreactive elements
14. a reaction that takes place when two or more substances react to form new substances
15. description of how a substance interacts with other substances, such as acids;chemical properties are observable only when a chemical change occurs
18. pure substance formed when non-metals combine
21. catalyst involved in chemical reactions in living things
22. atom that has become electrically charged because it has lost or gained electrons; a positive ion is an atom that has lost one or more electrons;a negative ion is an atom that has gained one or more electrons
24. the smallest part of an element that is representative of that element; a neutral particle made up of a nucleus containing protons and neutrons, and in which the number of electrons equals the number of protons
25. mass of one atom of an element calculated from the total number of protons,neutrons, and electrons of that atom; measured in atomic mass units (amu)

1. anything that has mass and occupies space
2. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
4. number of protons in the nucleus of one atom of an element
5. group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
6. element that has both metallic and non-metallic properties
7. change of state from a solid to a liquid
9. group of atoms joined by covalent bonds
12. orbit of electrons around the nucleus of an atom
13. invisible negatively charged particle that orbits the nucleus of an atom
16. measure of atomic mass; 1 amu is equal to 1/12th the mass of a carbon 12 atom
17. pure substance formed when at least one metal and one non-metal combine
19. change that results when two or more substances react to create a different substance or substances; the new substances have completely different properties from the original ones
20. neutral particle in the nucleus of an atom
23. combination of pure substances; unlike a compound, the components of a mixture do not combine chemically and are not always in the same ratio