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57											58											59

Across 4. developed the first atomic theory 8. the triad of metals that included copper, gold, and silver 9. soft silvery metal 10. can change to a gas easily at room temperature 13. elements in groups 3-12 14. a drying agent 16. poisonous green gas 18. reaction in which energy is absorbed 20. the 4th phase of matter found in stars 23. elements #89-103 25. he thought that atoms were the smallest particles of matter and different types of atoms exist 27. group 17 elements 31. he did not believe that atoms could be made of empty space 35. group 2 elements 37. describes the characteristics and behavior of matter and changes it undergoes 40. group of atoms covalently bonded together when they share electrons 41. the octet rule states that atoms become stable when they have this many valence electrons 43. science that investigates and explains the structure and properties of matter 47. reaction in which energy is released 49. only liquid metal 51. compound that conducts electricity when dissolved in water 52. nonmetal, reacts at high temperatures, releases CO2 when burned 53. negative ion 54. amount of matter in a certain volume 56. examples of this are O2 and O3 57. changes from a gas to a liquid at -183 degrees Celsius 58. his discoveries led to the law of definite proportions 59. horizontal row

Down 1. his view of the atom had the electrons orbiting a central positive nucleus 2. this is made of an n-type and a p-type semiconductor 3. tendency to recur at regular intervals 5. element commonly known to be used in diodes and transistors 6. specific ratio of water to ionic compounds 7. testable prediction to explain observations 11. developed law of conservation of matter 12. simplest hydrocarbon 15. substance that takes up enough water from air to dissolve completely and form a solution 17. white crystalline solid 19. type of covalent bond that shares 2 pairs of electrons 21. process of separating liquids by using their boiling points 22. simplest ratio of ions in an ionic compound 24. explanation based on many observations and supported by several results 26. elements in groups 1-2 and 13-18 28. elements that conduct electric currents under certain conditions 29. he grouped elements in groups of 3 called triads 30. substance that has all the water removed 32. type of covalent bond nitrogen forms with itself 33. regular repeating arrangement of atoms, ions, or molecules 34. changes from a gas to a solid at -80 degrees Celsius 36. modern periodic table lists the elements according to this property 38. the positive ends of the cathode ray tube 39. electromagnetic radiation travels in this form 42. scientist that discovered the electron 44. most abundant element in the universe 45. he used gold foil to discover the nucleus 46. capacity to do work 48. particle accelerators are used to produce these types of elements 50. anything that has mass and takes up space 52. positive ion 55. measures the amount of matter in an object