chemistry crossword

3. invisible negatively charged particle that orbits the nucleus of an atom
7. an experiment in which one or more products of a chemical reaction can escape
10. neutral particle in the nucleus of an atom
11. element that has both metallic and non-metallic properties
13. chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
16. new substance produced in a chemical reaction between reactants
17. 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
18. group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
19. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
20. a material that electric charge can move through easily
21. property that describes the physical appearance and composition of a substance
22. the sum of the number of protons and neutrons in an atom
23. that have a density of 5 or higher e.g., copper, zinc, lead, mercury, cadmium,nickel heavy metals are one type of substance monitored to determine water quality

1. catalyst involved in chemical reactions in living things
2. chemical combination of two or more elements in a specific ratio
4. description of how a substance interacts with other substances, such as acids;chemical properties are observable only when a chemical change occurs
5. substance that helps a chemical reaction to proceed more quickly
6. positively charged center of an atom;contains protons and neutrons
8. change in the appearance or state of a substance that does not change the composition
9. a table in which the elements are organized by their physical and chemical properties
12. a reaction that takes place when two or more substances react to form new substances
14. atom that has become electrically charged because it has lost or gained electrons a positive ion is an atom that has lost one or more electrons a negative ion is an atom that has gained on
15. substance that strongly resists the flow of electricity
17. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
24. 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