chemistry crossword

3. A combination of more than one element
4. Law of physics that states that the total energy of an isolated system does not increase or decrease.
6. A species with an overall positive charge
7. A species with an overall negative charge
8. The centre of an atom that contains protons and neutrons
9. A gas law that relates volume and temperature at constant pressure and amount
12. A compound that increases the amount of H+ ions in an aqueous solution
14. A compound that increases the amount of OH− ions in an aqueous solution
15. The specific set of principal, angular momentum, and magnetic quantum numbers for an electron.
17. Atoms of the same element that have different numbers of neutrons
20. The number of things equal to the number of atoms in exactly 12 g of carbon-12; equals 6.022×1023 things
21. neutral subatomic particle

1. are located to the far right of the periodic table and make up the eighteenth column
2. negatively charged subatomic particle
5. A gas law that relates pressure and volume at constant temperature and amount
10. the hardest part of chemistry
11. the chemical elements in group one of the periodic system
13. the science that deals with the properties, composition, and structure of substances
16. An element that exists in various colors and phases, is brittle, and does not conduct electricity or heat well
18. a positive charged subatomic particle
19. A physical combination of more than one substance