Radiometric Dating (tap anywhere)

Protons Neutrons Electrons

Elements on the periodic table are STABLE Elements can have radioactive versions of itself called ISOTOPES!! Page 1 in your ESRT has your list! Lets see how these elements become radioactive!!

Period 1 2 3 4 5 6 7 6.941 3 19 Na 2-8-8-1 Li 2-1 22.98977 11 85.4678 37 1 1.00794 H 1 1 1 Rb 2-8-18-8-1 132.905 Cs +1 1 2-8-1 39.0983 K +1 55 2-8-18-18-8-1 (223) +1 Fr 87-18-32-18-8-1 Group 2 +1 9.01218 Be 4 2-2 +1 24.305 +1 +1 Mg 12 2-8-2 87.62 Sr 38 2-8-18-8-2 137.33 Ba 56 40.08 Ca 20 2-8-8-2 Ra 88-18-32-18-8-2 88.9059 39 138.9055 La 57 2-8-18-18-9-2 89 Y 2-8-18-9-2 2-8-18-18-8-2 (226) (227) 3 44.9559 Sc 21 2-8-9-2 Ac -18-32-18-9-2 47.867 Ti 22 2-8-10-2 91.224 Zr 40 2-8-18-10-2 178.49 Hf 72 (261) Rf 104 4 KEY 50.9415 V 23 *18-32-10-2 (262) 51.996 Cr 24 2-8-11-2 2-8-13-1 92.9064 Nb 95.94 +5 41 2-8-18-12-1 180.948 Ta 73-18-32-11-2 105 5 Periodic Table of the Elements Atomic Mass Symbol Atomic Number Electron Configuration Db +5 +5 6 Mo 42 2-8-18-13-1 +6 +6 183.84 +6 W 74-18-32-12-2 (266) Sg 106 12.011 4 6 2-4 54.9380 C 7 Mn 25 2-8-13-2 (98) Tc 43 2-8-18-13-2 186.207 Re 75-18-32-13-2 (272) Bh 107 Group +7 +6 +7 +6 +7 55.845 Fe 26 2-8-14-2 101.07 Ru 44 2-8-18-15-1 190.23 8 Os 76-18-32-14-2 (277) Hs 108 58.9332 Selected Oxidation States Relative atomic masses are based on 12 C = 12 (exact) Note: Numbers in parentheses are mass numbers of the most stable or common isotope. 9 Co 27 2-8-15-2 102.906 Rh 45 2-8-18-16-1 192.217 Ir 77-18-32-15-2 (276) Mt 109 58.693 Ni 28 2-8-16-2 106.42 Pd 46 2-8-18-18 195.08 Pt 78 63.546 +1 Cu 2-8-18-1 107.868 Ag 47 2-8-18-18-1 196.967 79 Au -18-32-17-1 -18-32-18-1 (281)Ds (280) 110 10 29 11 12 Rg 111 +1 +1 65.409 Zn 30 2-8-18-2 112.41 Cd 48 2-8-18-18-2 200.59 Hg 80-18-32-18-2 (285) Cn 112 10.81 B 5 2-3 26.98154 Al 13 2-8-3 69.723 Ga 31 2-8-18-3 114.818 +1 49 In 2-8-18-18-3 12.011 C 6 2-4 204.383 +1 Tl 81-18-32-18-3 28.0855 Si 14 2-8-4 Pb 4 4 72.64 Ge 32 2-8-18-4 118.71 Sn 50 2-8-18-18-4 207.2 82-18-32-18-4 (289) Uuq 114 14.0067 N 7 2-5 30.97376 P 15 2-8-5 74.9216 As 33 2-8-18-5 121.760 Sb 51 2-8-18-18-5 208.980 Bi 83-18-32-18-5 3 2 1 +1 +5 3 +5 15.9994 O 8 2-6 32.065 S 16 2-8-6 3 +5 3 +5 +5 78.96 Se 34 2-8-18-6 127.60 Te 52 2-8-18-18-6 2 18.9984 2 +6 2 +6 2 +6 (209) Po 84-18-32-18-6 9 2-7 F 35.453 Cl 17 2-8-7 79.904 Br 35 2-8-18-7 126.904 l 53 2-8-18-18-7 (210) At 85-18-32-18-7 4.00260 He 2 2 Group 13 14 15 16 17 18 (284) Uut 113** (288) Uup 115 (292) Uuh 116 1 20.180 Ne 10 1 +1 +5 +7 1 +1 +5 1 +1 +5 +7 (? ) Uus 117 2-8 39.948 Ar 18 2-8-8 18 83.798 Kr 36 2-8-18-8 131.29 Xe 54 2-8-18-18-8 (222) Rn 86-18-32-18-8 0 0 0 0 0 +6 0 (294) Uuo 118 140.116 Ce 58 140.908 Pr 59 144.24 Nd 60 (145) Pm 61 150.36 Sm 62 151.964 Eu 63 157.25 Gd 64 158.925 65 162.500 Dy 66 164.930 Ho 67 167.259 Er 68 168.934 Tm 173.04 Yb 70 174.9668 Lu 71 232.038 Th 231.036 Pa 238.029 +5 U +5 +6 90 91 92 (237)Np (244) Pu (243) Tb +5 93 +6 94 +5 +6 Am (247) Cm (247) Bk +5 +6 95 96 97 (251)Cf (252) Es (257) 69 98 99 Fm 100 (258) Md 101 (259) No 102 (262) Lr 103 *denotes the presence of (2-8-) for elements 72 and above **The systematic names and symbols for elements of atomic numbers 113 and above will be used until the approval of trivial names by IUPAC. Source: CRC Handbook of Chemistry and Physics, 91 st ed., 2010 2011, CRC Press

Group 13 14 15 1 10.81 5 2-3 B 12.011 6 2-4 C 4 14.0067 7 2-5 N 3 2 1 +1 +5 15.999 8 2-6 O 26.98154 Al 28.0855 Si 4 30.97376 P 3 +5 32.065 S 2 13 2-8-3 14 2-8-4 15 2-8-5 16 2-8-6

Most Carbon has...

Most Carbon has... 6 Protons 6 Neutrons

6 Protons 6 Neutrons C-12 Stable and Happy :-)

But sometimes, Carbon has... 6 Protons 6 Neutrons

But sometimes, Carbon has... 6 Protons 8 Neutrons

6 Protons 8 Neutrons C-14 Unstable and Unhappy :-(

C-14 is RADIOACTIVE

C-14 6 Protons 8 Neutrons

Group 13 14 15 1 10.81 5 2-3 B 12.011 6 2-4 C 4 14.0067 7 2-5 N 3 2 1 +1 +5 15.999 8 2-6 O 26.98154 Al 28.0855 Si 4 30.97376 P 3 +5 32.065 S 2 13 2-8-3 14 2-8-4 15 2-8-5 16 2-8-6

N-14 7 Protons 7 Neutrons

C-14 RADIOACTIVE N-14 DECAY Unstable Unhappy (Parent Isotope) Stable Happy (Daughter Product)

C-14 is really important, but there are others!

K-40 RADIOACTIVE Ar-40 DECAY Unstable Unhappy (Parent Isotope) Stable Happy (Daughter Product)

U-238 RADIOACTIVE Pb-206 DECAY Unstable Unhappy (Parent Isotope) Stable Happy (Daughter Product)

Rb-87 Unstable Unhappy (Parent Isotope) RADIOACTIVE DECAY Sr-87 Stable Happy (Daughter Product)

Parent Isotope = Radioactive

Daughter Product = Decay Product

So what?

So what? Radioactive decay happens at a predictable rate called a half-life.

Radioactive Decay Data RADIOACTIVE ISOTOPE DISINTEGRATION HALF-LIFE (years) Carbon-14 14 C 14 N 5.7 10 3 Potassium-40 40 K 40 Ar 40 Ca 1.3 10 9 Uranium-238 238 U 206 Pb 4.5 10 9 Rubidium-87 87 Rb 87 Sr 4.9 10 10 Equations

It takes 5,700 years for half of a sample of C-14 to decay into N-14.

We can determine the age of a rock by looking at the ratio of the radioactive substance to it s product.

Example: How old is a rock that is made up of 50% C-14 and 50% N-14? Because there is half of each substance, 1 half-life has gone by. The half-life of C-14 is 5,700 years, so this rock is 5,700 years old.

C-14 is used to date relatively young (last 60,000 years), organic materials. (short half life) Potassium and Uranium are used to date older rocks (really long half life)!

C-14 is used to date Wooly Mammoth Hair < LAST HOME

Potassium and Uranium are used to date old fossils, like this trilobite < LAST HOME

You CANNOT change the half-life of a radioactive substance!!

On the graph provided, please plot a line to represent the decay of the C-14 and a second line to represent the growth of the N-14. Be sure to draw smooth, curving lines using a different color for each element. Include a key.! At each point show the number of half lives and the percentage of material remaining at that point.!

How old is this ancient skull?

Time Passed: 0 years # of Half Lives: 0 CARBON-14 (Radioactive Parent Material)! PERCENT: 100% ATOMS: 260 NITROGEN-14 (Stable Daughter Material)! PERCENT: 0% ATOMS: 0

Time Passed: 5,700 years # of Half Lives: 1 CARBON-14 (Radioactive Parent Material)! PERCENT: 50% ATOMS: 130 NITROGEN-14 (Stable Daughter Material)! PERCENT: 50% ATOMS: 130 < LAST HOME

Time Passed: 11,400 years # of Half Lives: 2 CARBON-14 (Radioactive Parent Material)! PERCENT: 25% ATOMS: 65 NITROGEN-14 (Stable Daughter Material)! PERCENT: 75% ATOMS: 195 < LAST HOME

Time Passed: 17,100 years # of Half Lives: 3 CARBON-14 (Radioactive Parent Material)! PERCENT: 12.5% ATOMS: 32.5 NITROGEN-14 (Stable Daughter Material)! PERCENT: 87.5% ATOMS: 227.5 < LAST HOME

Time Passed: 22,800 years # of Half Lives: 4 CARBON-14 (Radioactive Parent Material)! PERCENT: 6.75% ATOMS: 16.25 NITROGEN-14 (Stable Daughter Material)! PERCENT: 93.25% ATOMS: 243.75 < LAST HOME

Time Passed: 28,500 years # of Half Lives: 5 CARBON-14 (Radioactive Parent Material)! PERCENT: 3.375% ATOMS: 8.25 NITROGEN-14 (Stable Daughter Material)! PERCENT: 96.625% ATOMS: 251.75 < LAST HOME

Check your graph against the one on the following page. When you re done, complete the questions on the upcoming slides. Record your answers in the space provided on the lab sheet.!

300 Atoms of C-14 Atoms of N-14 225 260 228 244 252 A t o m s 150 130 195 75 65 33 0 Start 0 2 Half-lives (11,400) 4 Half-lives (22,800) 7 8 Number of Half-lives (how HOME many years have passed) < LAST

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QUESTION #13 Here are some additional problems you can try if you finish this lab before other students are finsished.

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