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Across 1. scientists make ______ to forecast what will happen in the future based on past evidence or experience (Fact 16) 6. the ____ _____ of an atom is equal to the number of protons in the nucleus of an atom (Fact 250) 8. sublimation is when a solid changes directly to a gas without passing through its' liquid state first ; dry ice is an example (Fact 234 9. _______ have no electrical charge (Fact 242) 11. ______ is when a gas changes to a liquid (Fact 236) 12. During a chemical reaction,chemical bonds between atoms are _______ and new ones are formed (Fact 277) 14. each proton has a mass of 1 amu, each neutron has a mass of 1 amu and each electron is given a mass of ____ amu (Fact 248) 16. scientists make _______ when they uses their senses to gain information (Fact 14) 17. litmus paper is an example of an indicator; acids turn _____ litmus paper red and bases turn red litmus paper blue (Fact 292) 20. in a ________ reaction an acid reacts with a base to produce a salt and water (Fact 295) 21. ______ have a positive electrical charge (Fact 241) 22. Newton's second law of motion states that the _______ of an object depends on the mass of the object and the amount of force applied (Fact 125) 23. a chemical formula is a shorthand way to use chemical symbols and________ to represent a substance (Ex CO represents carbon dioxide ) (Fact 27 26. condensation, freezing and *deposition are ______ changes of state; during these changes the substance releases heat energy and particle motion decreases (Fact 238) 27. an _____________ is a substance that changes color in the presence of an acid or base (Fact 291) 28. the _____ _____ ranges from 0 (very acidic) to 14 (very basic) (Fact 293) 29. _______ is a type of vaporization that occurs only on the surface of a liquid and below the liquid's boiling point (Fact 232) 30. ______, vaporization and sublimation are endothermic changes of state; during these changes the substance absorbs heat energy and particle motion increases (Fact 235)

Down 2. a ____ ______ uses chemical symbols and formulas as a short way to describe a chemical reaction (Fact 280) 3. To describe a reaction accurately, a chemical equation must be ________ or show the same number and type of atoms on each side of the equation (Fact 281) 4. _______ have a negative electrical charg (Fact 243) 5. most nonmetals except for ________ are found to the right of the zigzag line on the Periodic Table and most are gases at room temperature (Fact 267) 7. a _________ is a compound that tastes bitter, feels slippery, conducts electricity and has a pH of greater than 7 (Fact 290) 10. Newton's first law of motion states that the motion of an object will not change in no _______ force acts upon it (Fact 122) 13. Newton's third law of motion states that whenever one object exerts a force on a second object, the second object exerts and equal and ______ force on the first (Fact 126) 15. the ____ _____ of an atom is equal to the sum of its protons and neutrons (Fact 251) 18. scientists make ______ or reasoned judgments to explain observations (Fact 15) 19. _______ is when a liquid changes to a gas (Fact 231) 24. _______ is a type of vaporization that occurs throughout a liquid and at its' boiling point (Fact 233) 25. an ________ is a compound that reacts with metals, tastes sour, conducts electricity, can destroy body tissue and has a pH of less than 7 (Fact 289)