Periodic Table

2. symbol for atomic mass unit
6. a neutral subatomic particle in the nucleus of an atom.
11. atomic massthe weighted average of the masses of all naturally occuring isotopes of an elementmetal
13. a region in an atom where there is a high probability of finding electrons
15. or a group of atoms that has lost or gained one or more electrons and therefore has a net electric charge
16. any atoms having the same number of protons but a different number of neutrons
17. anion with a positive changed
18. the center of an atom; made up of protons and neutrons
19. the smallest particle that has the properties of an element.
20. level any of the possible energies an electron may have in an atom.

1. number of protons in the nucleus of an atom
3. properties of elements tend to repeat in a regular pattern when elements are arranged in order of increasing atomic number
4. the process of adding electrons to or removing electrons from an atom or group of atoms
5. unita quantity equal to one-twelfth the mass of a carbon-12 atom
7. a positively charged subatomic particle in the nucleus of an atom.
8. a horizontal row of elements in the periodic table
9. a negatively charged subatomic particle found in the energy level of an atom
10. vertical column of elements in the periodic table
12. electron-an electron in the outermost energy level of an atom
14. the total number of protons and nutrons in the nucleus of an atom