chemistry crossword

7. catalyst involved in chemical reactions in living things
8. substance made of only one kind of matter, which has a unique set if properties
10. invisible negatively charged particle that orbits around the nucleus of an atom
14. change in the appearance or state of a substance that does not change the composition
15. descriptions of a substance that can be pounded or rolled into sheets
17. chemical reaction that releases energy
18. pure substance formed when non-metals combine
20. 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
21. atoms that have become electrically charged because it has lost or gained electrons
22. change of state from solid to a gas or from a gas to a solid
24. pure substances formed when at least one metal or non-metal combine
25. positively charged particle in the nucleus of an atom

1. neutral particle in the nucleus of an atom
2. chemical combination of two or more elements in a specific ratio
3. anything that has mass and occupies space
4. pure substance that cannot be broken down into other substances; a substance made up of only one type of atom
5. combination of pure substances; unlike a compound, the components of a mixture do not combine chemically and are not always in the same ratio
6. group 18 elements in the periodic table; the most stable and nonreactive elements
9. chemical reaction that absorbs energy
11. number of protons in the nucleus of one atom of an element
12. positively charged that centre of an atom; contains protons and neutrons
13. shiny, malleable, ductile element that conducts electricity
16. property that describes the physical appearance and composition of a substance
19. substance that strongly resists the flow of electricity
23. vertical column of elements in the periodic table; elements in a family all have similar chemical properties; also called a family