Across
- 2. slow chemical change that occurs when oxygen in the air reacts with a metal
- 8. number of protons in the nucleus of one atom of an element
- 9. ability of a substance to conduct electricity or heat
- 10. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
- 11. a reaction that takes place when two or more substances react to form new substances
- 12. chemical reaction that releases eenergy
- 14. description of how a substance interacts with other substances, such as acids;chemical properties are observable only when a chemical change occurs
- 18. principle that matter is not created or destroyed in a chemical reaction; the mass of the products always equals the mass of the reactants
- 22. metals group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
- 23. chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
- 25. an experiment in which all reactants and all products of a chemical reaction are accounted for
Down
- 1. substance that helps a chemical reaction to proceed more quickly
- 2. 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
- 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. catalyst involved in chemical reactions in living things
- 5. chemical reaction that absorbs energy
- 6. vertical column of elements in the periodic table; elements in a family all have similar chemical properties; also called a family
- 7. invisible negatively charged particle that orbits the nucleus of an atom
- 13. measure of atomic mass; 1 amu is equal to 1/12th the mass of a carbon 12 atom
- 15. compound that dissolves in water to form a solution with a pH lower than 7
- 16. (CO(g))colourless, odourless gas;produced by incomplete combustion of chemicals containing carbon (e.g. hydrocarbons); major source: motor vehicles
- 17. chemical combination of two or more elements in a specific ratio
- 19. orbit of electrons around the nucleus of an atom
- 20. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
- 21. cloudy mixture in which tiny particles of one substance are held within another and particles cannot be separated out from the other substance
- 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