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Nuclear Chemistry

Unit 4. Nuclear Chemistry. Radiation. In this part of the unit , we will focus on the nucleus ! It’s very small ( 10 -13 cm) It’s very dense ( 1.6 × 14 g/cm 3 ) A lot of energy holds it together! ( millions of times more than involved in chemical reactions!).

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Nuclear Chemistry

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  1. Unit 4 Nuclear Chemistry

  2. Radiation • In this part of the unit, we will focus on the nucleus! • It’s very small (10-13 cm) • It’s very dense (1.6 ×14 g/cm3) • A lot of energy holds it together! (millions of times more than involved in chemical reactions!)

  3. Many nuclei are RADIOACTIVE! • They spontaneously decompose or DECAY (break apart) • forming a different nucleus & producing one or more particles

  4. 3 Main Types of Decay Particles • Alpha (α) particles • Slow moving nucleus of a helium atom. • Not very dangerous, can be stopped by • Skin • A piece of paper

  5. 3 Main Types of Decay Particles • Beta ( β) Particles • Faster moving electrons • Are harmful • Can be stopped by wood or metal sheets

  6. 3 Main Types of Decay Particles • Gamma (γ) Particles • High-energy photon of light • Very dangerous • Partially stopped by 6 inches of lead or 6 feet of concrete

  7. Half-Life (t1/2) • Time it takes for half of a radioactive material to decay away. • Example: • You have 100.g of Ra-221. It’s half-life is 30 seconds. • What does that mean? • How much Ra-221 would be left after 90 seconds?

  8. More Half-Life Problems • The half-life of I-131 is 8.02 days. How much I-131 is left after 32.08 days? You originally have 600.g. • The half-life of Pu-239 is 24,360 years. Starting with 1000.g, how much would be left after 146,160 years? • Would it ever completely decay away?

  9. Half-Life Equation • t1/2 = mass of material 2# of half-lives • Let’s try it!

  10. Fission • Process of splitting a heavy nucleus into two more stable nuclei with smaller mass numbers • Releases a lot of energy

  11. Fission • Chain reaction • When you have a lot of a radioactive substance and the fission of one nucleus gives off particles that hit other nuclei that give off more particles that hit more nuclei. . .

  12. Fission • Critical Mass • The mass of material required to produce a chain reaction.

  13. Fusion • Process of combining two light nuclei to form a heavier, more stable nucleus. • Produces a lot more energy than fission!

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