Across
- 1. 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
- 5. (in chemistry) vertical column of elements in the periodic table; elements in a family all have similar chemical properties; also called a group
- 8. chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
- 11. chemical reaction that takes place in cells; food (sugar) reacts with oxygen to produce energy, water, and carbon dioxide
- 14. 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
- 15. group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
- 20. chemical reaction that releases energy
- 22. change of state from a gas to a solid
- 24. number of protons in the nucleus of one atom of an element
- 25. unit measure of atomic mass; 1 amu is equal to 1/12 the mass of a carbon 12 atom
Down
- 1. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
- 2. cloudy mixture in which tiny particles of one substance are held within another and particles cannot be separated out from the other substance
- 3. reaction that takes place when two or more substances react to form new substances
- 4. change of state from a gas to a liquid
- 6. slow chemical change that occurs when oxygen in the air reacts with a metal
- 7. chemical reaction that absorbs energy
- 9. description of a solid that can be stretched into a long wire
- 10. principle that matter is not created or destroyed in a chemical reaction; the mass of the products always equals the mass of the reactants
- 12. substance that helps a chemical reaction to proceed more quickly
- 13. description of how a substance interacts with other substances, such as acids;chemical properties are observable only when a chemical change occurs
- 16. change of state from a liquid to a solid
- 17. amount of mass in a given volume of a substance
- 18. catalyst involved in chemical reactions in living things
- 19. chemical combination of two or more elements in a specific ratio
- 21. combination of symbols that represent a compound; the formula identifies the elements in the compound and the amount of each element
- 23. ability of a substance to conduct electricity or heat