Crossword Puzzel

2. valuable because they are radioactive
6. elements that are good at conducting heat and electricity have a shiny appearance and are located on the far left of the periodic table
7. a combination of protons and neutrons
9. metals, earth metals that are reactive with mainly water
11. process by which atoms produce energy and particles
13. formed when an atom loses or gains one or more electrons
15. each horizontal row in the periodic table
18. decay, a transformation of one element to another
21. a negatively charged particle
22. found on the far right side of the periodic table poor heat and electricity conductors have a dull appearance
24. atoms of the same element that have a different number of neutrons

1. elements in group 17 very reactive nonmetals that easily form salts with other metals
3. gases, elements that almost never react with other metals
4. number, the number of protons in the nucleus
5. rare earth elements that are referred to as lanthanides because they follow the element lanthanum
7. ion, molecules in the air/atmosphere charged with electricity
8. elements that have properties of metals and nonmetals
10. metals, elements in groups 3-12 generally less reactive
12. cloud, any place an electron can be at any time when measured
14. a positively charged particle
16. metals, very reactive located in group 1 of the periodic table
17. atomic mass unit
19. a negatively charged particle
20. elements in a verticle row in the periodic table
23. ion, can be formed from an atom and has a positive charge