Across
- 5. substance that helps a chemical reaction to proceed more quickly
- 6. change of state from a gas to a liquid
- 7. dull, brittle element that does not conduct electricity
- 8. measure of atomic mass; 1 amu is equal to 1/12 the mass of a carbon 12 atom
- 10. energy stored in chemicals and released when chemicals react; a form of potential or stored energy
- 18. a reaction that takes place when two or more substances react to form new substances
- 19. chemical reaction that takes place in cells; food (sugar) reacts with oxygen to produce energy, water, and carbon dioxide
- 20. chemical combination of two or more elements in a specific ratio
- 21. chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
- 22. 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
- 24. group 18 elements in the periodic table;the most stable and unreactive elements
Down
- 1. ability of a substance to conduct electricity or heat
- 2. group 1 elements in the periodic table, not including hydrogen;the most reactive of the metals
- 3. 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)
- 4. number of protons in the nucleus of one atom of an element
- 6. cloudy mixture in which tiny particles of one substance are held within another and particles cannot be separated out from the other substance
- 9. principle that matter is not created or destroyed in a chemical reaction; the mass of the products always equals the mass of the reactants
- 11. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
- 12. chemical reaction that absorbs energy
- 13. description of how a substance interacts with other substances, such as acids;chemical properties are observable only when a chemical change occurs
- 14. chemical reaction that releases energy
- 15. group 2 elements in the periodic table; their reactivity is not as strong as that of that alkali metals
- 16. 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
- 17. an experiment in which all reactants and all products of a chemical reaction are accounted for
- 23. group 17 elements in the periodic table;the most reactive non-metals