Chemistry crossword

3. combination of pure substances; unlike acompound, the components of a mixture do not combine chemically and are not always in the same ratio
5. vertical column of elements in the periodic table; of elements in a family all have similar chemical properties; also called a family
8. positively charged centre of an atom contains protons and neutrons
9. change from liquid to soild
11. an experiment in which one or more products of a chemical reaction can escape
15. elements and compounds that organisms need for living, growing, and reproducing
18. compound made up of units calledamino acids; protein molecules contain atoms ofnitrogen, hydrogen, oxygen, and carbon
19. substance that helps a chemical reaction to proceed
24. group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
25. group 18 elements in the periodic table;the most stable and unreactive elements

1. amount of mass in a given voilume of a substance
2. that describes a particularsubstance (e.g., colour, lustre, melting point,crystal shape, solubility, density)
4. atom that has become electrically charged because it has lost or gained electrons; a positiveion is an atom that has lost one or more electrons;a negative ion is an atom that has gained one ormore electrons
6. new substance produced in a chemical reactants between reactents
7. catalyst involved in a chemical reaction in living things
10. substance that reacts with another substance or substances in a chemical reaction to create new substances with different propertier
12. homogeneous mixture; mixture of two or more pure substances that looks like one substance
13. mass of a substance that can dissolve in a given amount of solvent to form a saturated solution at a given temperature
14. positively charged particle in the nucleus of an atom
16. substance made of only one kind of matter, which has a unique set of properties
17. group 17 elements in the periodic table;the most reactive non-metals
20. number of protons in the nucleus of one atoms
21. (SO2(g))forms when sulfur combines swith oxygen in the air; major air pollutant that forms both smog and acid rain; major source:industrial processes
22. chemistry) vertical column of elements in the periodic table; elements in a family all have similar chemical properties; also called a group
23. group of atoms joined by covalent bond