chemistry crossword

3. characteristics that describe a particular substance (e.g. colour, lustre, melting point)
4. group 1 elements in the periodic table, not including hydrogen
5. change in the appearance or state of a substance that does not change the composition
12. pure substance formed when at least one metal and one non-metal combine
14. anything that has mass and occupies space
18. pure substance formed when non-metals combine
21. netrual particle in the nucleus of an atom
22. vertical column of elements in the periodic table
23. positively charged centre of an atom; contains protons and neutrons
24. a system of easy-to-see warning symbols on hazardous materials

1. horizontal row of elements in the periodic table
2. positively charged particle in the nucleus of an atom
3. a table in which the elements are organized by their physical and chemical properties
6. group 17 elements in the periodic table
7. combination of symbols that represent a compound
8. occurs when two or more materials react and create new materials
9. the ability of a substance to conduct electricity or heat
10. mass of one atom of an element calculated from the total number of protons, neutrons, electrons of that atom
11. a chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
13. made of only one kind of matter
15. amount of mass in a given volume of a substance
16. group of atoms joined by covalent bonds
17. group of atoms acting as one
19. a reaction that takes place when two or more substances react to form new substances
20. measure of one atomic mass