Matter and Chemical Change

5. chemical reaction that absorbs energy
6. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
8. cloudy mixture in which tiny particles of one substance are held within another and particles cannot be separated out from the other substance
9. chemical combination of two or more elements in a specific ratio
11. number of protons in the nucleus of one atom of an element
13. 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
15. orbit of electrons around the nucleus of an atom
16. group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
19. a reaction that takes place when two or more substances react to form new substances
21. invisible negatively charged particle that orbits the nucleus of an atom
22. pure substance that cannot be broken down into other substances; substance made up of only one type of atom
24. 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)
25. change of state from a gas to a liquid

1. chemical reaction that takes place in cells; food (sugar) reacts with oxygen to produce energy, water, and carbon dioxide
2. a solution in which water is the solvent
3. 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
4. ability of a substance to conduct electricity or heat
7. an experiment in which all reactants and all products of a chemical reaction are accounted for
10. description of how a substance interacts with other substances, such as acids; chemical properties are observable only when a chemical change occurs
12. slow chemical change that occurs when oxygen in the air reacts with metal
14. chemical reaction that releases energy
15. catalyst involved in chemical reactions in living things
17. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
18. measure of atomic mass; 1 amu is equal to 1/12th the mass of a carbon 12 atom
20. description of a solid that can be stretched into a long wire
23. substance that helps a chemical reaction to proceed more quickly