2. PS-2.2 Illustrate the fact that the atoms of elements exist as stable or unstable isotopes.

3. Opener- Write the chart & fill it in ProtonsNeutronsElectrons Symbol Mass (heavy/light) Location Charge Does it affect ID? Does it affect mass? Does it affect volume

4. Opener Study 1 st 15 elements Turn in hw ½ sheet into the front basket

5. * atomic number – found on the periodic table, = # p+, identifies the atom * mass number - # protons + # neutrons * atomic mass - weighted average of the masses of the naturally occurring isotopes of an element. Opener 1/23/07

6. * Isotope – atoms of the same element with the same # p, different # neutrons * nuclear decay - a nuclear reaction that involves emission of energy or particles from the nucleus, resulting in a more stable nuclear environment * radiation - describe the particles and/or energy that are emitted during nuclear decay. (Alpha, and beta particles, and gamma rays) Opener 1/23/07

7. Atomic Number equal to the number of protons, always the same for a given element found on the periodic table since it is the same for all atoms of that element, it is always a whole number. Atomic number 47 Ag Silver 107.87 Atomic number

8. Mass Number atoms of the same element may have different numbers of neutrons the sum of that atom’s protons and neutrons can only be found on the periodic table for stable atoms, cannot be found on the periodic table for an isotope

9. Atomic Mass the weighted average of the masses of the naturally occurring isotopes of an element found on the periodic table it is an average, so usually not a whole number 17 Ag Silver 107.87 Atomic mass

10. Atomic Mass

11. Isotopes two or more atoms of the same element having the same number of protons but different numbers of neutrons (and therefore different masses) different numbers of neutrons, so they have different mass numbers Brittany

12. Isotopes

13. Carbon-14 Carbon-16 Atomic # 6 Atomic Mass 14….. Mass # 14 # protons 6 # neutrons 8 # electrons 6 Atomic # 6 Atomic Mass 16….. Mass # 16 # protons 6 # neutrons 10 # electrons 6

14. Isotope Notation C (mass #) 12 (Atomic #) 6 (Symbol) C - 12 (Symbol) (Mass #)

15. Unstable isotopes In order for a nucleus to be stable, there must be enough neutrons present to block the repulsive forces among the protons An unstable isotope of an element is radioactive (gives off radiation)

16. Due to the unstable condition of the nucleus, radioactive isotopes undergo nuclear decay –Nuclear decay is a nuclear reaction that involves emission of energy or particles from the nucleus, resulting in a more stable nuclear environment –Nuclear decay occurs naturally in many elements that are common on earth and there is always some radiation present in every environment –Radiation is the term used to describe the particles and/or energy that are emitted during nuclear decay (Alpha, and beta particles, and gamma rays)

17. What is defined as the sum of the p+ and the n 0 ???? Review

18. What defines the element?? Review

19. What is the weighted average of the masses of the naturally occurring isotopes of an element??? Review

20. An isotope is two atoms of the same element with the same # of ___ but a different # of _____ ???? Review

21. What are the two ways that we could write isotopic notation for the isotope Carbon - 18 ???? Review

22. In order for a nucleus to be stable, there must be enough ___ present to block the repulsive forces of the _____ ???? Review

23. What is nuclear decay ???? Review

24. What are the particles or energy emitted during nuclear decay called???? Review

25. What determines if an isotope will be stable or unstable????? Review