Chemistry crossword

2. a chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy
3. group of atoms joined by covalent bonds
4. anything that has mass and occupies space
6. made of only one kind of matter
7. horizontal row of elements in the periodic table
8. group 17 elements in the periodic table
10. group 1 elements in the periodic table, not including hydrogen
11. a system of easy-to-see warning symbols on hazardous materials
12. pure substance formed when non-metals combine
14. a table in which the elements are organized by their physical and chemical properties
15. pure substance formed when at least one metal and one non-metal combine
18. change in the appearance or state of a substance that does not change the composition
20. vertical column of elements in the periodic table
21. measure of one atomic mass
22. the ability of a substance to conduct electricity or heat

1. positively charged centre of an atom; contains protons and neutrons
2. combination of symbols that represent a compound
5. occurs when two or more materials react and create new materials
6. characteristics that describe a particular substance (e.g. colour, lustre, melting point)
9. netrual particle in the nucleus of an atom
13. a reaction that takes place when two or more substances react to form new substances
16. amount of mass in a given volume of a substance
17. positively charged particle in the nucleus of an atom
18. group of atoms acting as one
19. mass of one atom of an element calculated from the total number of protons, neutrons, electrons of that atom