1.  Grab the three worksheets on the front table  Write the Isotopic Notation for  Carbon-14  Iodine-128

2.  A half-life is the time required for one half of a sample of radioactive material to decay  Unlike chemical reactions, nuclear decay rates are constant regardless of temperature, pressure or surface area

3.  So, every X years, the substance will be reduced to half of its current amount.  If the half-life is 10 years, then every 10 years we will have ½ of the current amount.  If we have 80g of a substance with a half-life of 10 years, after 10 years we’ll have 40g. 10 years later, we’d have 20g. 10 years later we’d have 10g, and so on, and so forth.

4. Isotope: H-3 (Tritium)Half-Life: 12y 400g- 200g12y 100g24y 50g36y 25g48y 12.5g60y

6.  C-14 has a half life of 5730 years. If you have a sample of 50 grams. How much of the sample will be remaining after 1 half life? After 2 half lives? Step 1: Draw a T-Chart Step 2: Fill in amount and Half-Life Step 3: Multiply the amount by 2 Step 4: Add 1 Half-Life Step 5: Continue steps 3-4 until answer is achieved.

7.  After 4 years, only 2g remains of Isotope X, which has a half-life of 1 year. How much did I start with?  Step 1: Draw a T-Chart Step 2: Fill in FINAL amount and Half-Life Step 3: Multiply the amount up by 2 Step 4: Subtract up 1 Half-Life Step 5: Continue steps 3-4 until answer is achieved.

8.  Oh, come on, that’s easy.  9 years ago I put 10g of Isotope Y in a box. Today I opened it and there was only 2.5g left! What is the half-life of Isotope Y?  Step 1: Draw a T-Chart Step 2: Fill in amounts and final half-life value Step 3: Multiply the final amount by 2 until you get your original amount Step 4: How many times did you multiply by 2 to get your original amount? Divide your half-life by that #.

9.  I have 100g of element B that has a half-life of 10 years.  I have 50g of element A that has a half-life of 20 years.  Which would reach 12.5g first?

10.  Complete the worksheet labeled Half-life word problems – Physical Science.

11. Because many isotopes of atoms decay. But...why nuclides (nucleus of isotopes) decay? To obtain a stable ratio of neutrons to protons Stable Unstable (radioactive)

12. They become radioactive! Radioactivity: Emission of high-energy radiation from the nucleus of an atom

13. An alpha particle looks like a helium atom ( 4 2 He) mass reduces by 4 atomic # reduces by 2 Essentially, the atom just chucks 2 Neutrons and 2 Protons away.

15. ✦ Alpha decay (Remember, -4, -2) 224 86 Rn→ 251 98 Cf→ 25198 During Alpha radiation an atom's proton count drops by two, and we know what that means - a NEW element is formed!

16.  So, Neutrons. We said they’re ALMOST the same size as Protons?  Neutrons are actually just a Proton with an Electron inside of it!  That’s why they’re just a LITTLE heavier. About 1 electron heavier.

17. ✦ A beta particle is written 0 -1 e ✦ mass remains the same ✦ atomic # increases by 1 Ok, so this one’s weird. We throw away an electron, and in doing so, a Neutron becomes a Proton. Weird, right?

18. ✦ Beta decay (Remember, +0, +1) 120 50 Sn→ 137 56 Ba→  During Beta radiation an atom's proton count grows by one. Once again, NEW element!

19.  Gamma Decay:  Sometimes, elements get tired after decaying. It’s a lot of work, so they release a big burst of pure energy.  This is called Gamma Radiation.

20. ( 4 2 He) ( 0 -1 e) ( 0 0 )

21.  Nuclear fusion is the joining of two nuclei to form a heavier nuclei.  The reaction is followed either by a release or absorption of energy.  Fusion occurs in stars, such as the sun.

22. 2 H + 3 H → 4 He + 1 n + energy.

23.  The energy released by fusion is three to four times greater than the energy released by fission.

24.  Fission is the splitting of a nucleus that releases free neutrons and lighter nuclei.  The fission of heavy elements is highly exothermic which releases about 200 million eV compared to burning coal which only gives a few eV.

26.  Fission is used in nuclear power plants.