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			43

Across 6. substance that has all the water removed 9. compound that changes from a gas to a solid at -80 degrees celsius 10. specific ratio of water to ionic compound 12. an uncharged group of 2 or more atoms held together by covalent bonds 13. a combination of two or more substances in which the identity of each substance is not changed 14. he was able to predict properties of unknown elements based on location on the PT 18. the level that can be seen 19. his discoveries led to the law of conservation of matter 20. the level of the atoms 22. substances that take up enough water from air to dissolve completely and form a solution 23. element that is a nonmetal and reacts at high temperatures and releases CO2 when burned 25. the substance that is being dissolved in a solution 26. compounds that do not contain carbon 29. positive ion 31. tendancy to recur at regular intervals 33. isotopes have a different number of these particles 35. negative ion 36. can change to a gas easily at room temperature 39. group 17 elements 40. he was the first man to list the elements on the PT by atomic number 42. they proposed that matter is a combination of 4 elements 43. he did not believe that atoms could be made of empty space

Down 1. anything that has mass and takes up space 2. he proposed that electrons have enough energy to be in constant motion around the nucleus 3. soft, silvery metal in group 1 4. when atoms collide, these particles interact 5. he developed the law of definite proportions 7. element that is the most abundant in the universe 8. colorless, odorless, tasteless gas that supports burning 11. nitrogen trihydride, common inorganic compound 15. separating a liquid by the boiling points 16. He discovered the electron in an atom 17. simplest ratio of ions in an ionic compound 21. measure of the amount of matter an object contains 24. he used gold foil experiments to discover the nucleus 27. greenish poisonous gas 28. group 18 elements 30. an explanation based on many observation and supported by several results 32. triad of metals that included copper, gold and silver 34. dihydrogen monoxide 37. capacity to do work 38. positive ends of the cathode ray tube 41. inorganic compound that is an excellent conductor when dissolved in water