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Across 3. protons and neutrons are found in the _________ of an atom (Fact 250) 5. oceans cover about ___ _____ of Earth's surface (Fact 114) 8. __________ rays have the shortest wavelengths and highest frequencies and the greatest amount of energy; they can be used to kill cancer cells in the body (Fact 214) 10. The nucleus of an atom accounts for most of the _______ of an atom (Fact 252) 12. Neptune is the 8th planet from the sun and is known as the ______ Planet (Fact 64) 13. there are over 100 known elements that are organized on a chart called the _____ ______ (Fact 254) 14. ___________ is when a substance changes from a gas to a liquid (Fact 246) 16. _________ is the process that provides energy for the cell but does not require oxygen (Fact 168) 17. electromagnetic waves that people can see are called _______ _______ (Fact 212) 18. the electron cloud area of an atoms accounts for most of the _______ (space) in an atom (Fact 252) t 20. an ___________ is a trait that helps an organism survive (Fact 187) 21. protons carry a ______ electrical charge, neutrons carry no charge or a charge of zero and electrons carry a negative charge (Fact 251) 22. the __________ is Earth's solid rocky outer layer; it is made of the continents and islands and extends under the entire ocean floor (Fact 115)

Down 1. atoms are made of three __________ (smaller than the atom itself) particles called protons, neutrons, and electrons (Fact 249) 2. elements can be separated into three categories, metals, nonmetals and ______________ (semi-metals) Fact 255) 4. an __________ is the smallest particle into which an element can be divided and still be the same substance (Fact 248) 6. _________ is the process by which cells obtain energy from sugar (Fact 167) 7. the _______ _______ on the Periodic table is used to separate the metals from the nonmetals (Fact 256) 9. electrons are located in energy levels outside the nucleus in the _____ ______ area (Fact 250) 11. During ______ _______, there was plentiful volcanic activity, the atmosphere and oceans formed and multicellular organisms appeared (Fact 89) 15. _____________ is when a substance changes directly from a solid to a gas without passing through the liquid state first (Fact 244) 19. an ____________ is a pure substance that cannot be broken down into simpler substances by physical or chemical means (Fact 253)