1. Nuclear Chemistry

2. Reactions Chemical Nuclear Involve electrons
Affected external factors (temp, pressure, catalyst)
Involve the nucleus
Release WAY more energy
Not affected by external factors
Release about a million times more energy than chemical rxns.
Reactions

3. Electrostatic force Interaction between charged particles
like charges repel
opposite charges attract
Electrostatic force

4. How does the nucleus stay together?

5. Attractive force that acts between all nuclear particles that are extremely close together
Keeps the nucleus together
Much stronger than electrostatic force!
Strong Nuclear Force

6. The emission (and transmission) of energy through space in the form of waves or rays
Radiation

7. Radioactivity Alpha α Beta β Gamma γ Neutron n Proton p (electron) 4 2-1 1
Radioactivity 1

8. Contain two protons and two neutrons (A helium nucleus)
Symbol:
Carry +2 charge
Least penetrating form of radiation (only travels a few centimeter in the air)
Blocked by paper
Radioactivity-Alpha

9. Radioactivity-Beta Fast moving electrons Symbol: Charge: −1
medium penetration
(blocked by metal foil or wood)
Radioactivity-Beta

10. Radioactivity-Gamma High energy: waves or rays that possess no mass
Symbol:
Charge: none
Most penetrating and damaging type of radiation
not completely blocked by lead or concrete
Radioactivity-Gamma

11. Any element that spontaneously emits radiation (shows signs of radioactivity)
Transmutation—changing of an atom’s nucleus such that an new element is formed
Alpha, beta, and proton, not neutron or gamma
Transuranium elements-produced through induced transmutation
Radioactive

12. Why does an element go undergo transmutation?

13. Induced Transmutation
Before 1919, the only way to change the nucleus, or cause transmutation, was to wait for nature. In 1919, Rutherford was the first to induce transmutation which proved that nuclear reactions could be produced artificially.
Can occur by bombarding an atom with alpha particles, protons, or electrons
Induced Transmutation

14. Unstable (Radioactive) nuclei are found outside the band of stability
The stability of the nucleus depends on the neutron to proton ratio
If a nucleus is unstable, it will emit radiation (decay) to gain stability

15. Unstable nuclei (those that can be found outside the band of stability) losing energy by emitting radiation in a spontaneous process
Radioactive decay

16. Isotopes of atoms with unstable nuclei and go through radioactive decay to obtain a more stable nuclei
Small nuclei—up to 20 protons usually stable
Exception: Carbon—14
Large nuclei—tend to be radioactive, based on the ratio of neutrons to protons; ALL nuclei with 83 protons or more are radioactive
Radioisotope

17. In a balanced nuclear equation, mass numbers and atomic numbers are conserved
Alpha decay
Electron capture
or beta capture
Th  Ra He
230 90
226 88 4 2
Rb e → Kr
- 1 81 37 36
Nuclear Equations

18. Location in the equation
Reactant  Product
Word
Location in the equation
Bombardment
Reactant
Capture
Decay
Product
Emission (emit)
Vocab for Equations

19. Practice Zr  e + ? 2. Po  He + ? 3. ?  Rn + He 4. Ca  e + ?
5. Cm  He ? -1
218 84 4 2
222 86 97 40 47 20
244 96
Practice

20. Honors Only- write the equations and solve
Uranium-238 undergoing alpha emission
Krypton-81 undergoes beta capture
Cobalt-59 undergoes neutron bombardment, giving an alpha decay in addition to the new element
Would a)emission, b)capture, c) decay, d)bombardment be in the reactant or the product?
Honors students write equations in their notes
Honors Practice with words

21. Day 2 of Nuclear Chemistry

23. Time required for ½ of a radioisotope’s nuclei to decay into its products
Equation: NT = N0 (1/2)n
NT =Amount remaining at time T
N0 = initial amount
n= number of half-lives
Half-life

24. Half-Life Formula Example 1
Scientists start with 50.0 g sample of a radioisotope. How much is left after four half-lives?

25. Honors Half-Life Formula Ex 1
1. Scientists start with 50.0 g sample of a radioisotope. How much is left after four half-lives? NT = N0 (1/2)n NT =Amount remaining at time T N0 = initial amt n= number of half-lives NT = (50.0 g) (1/2)4 NT = g NT ≈ 3.13 g

26. CP Half-Life Formula Ex 1
Scientists start with 50.0 g sample of a radioisotope. How much is left after four half-lives?
Half-Life Skip count
50.0 g
25.0 g
12.5 g
6.25 g
3.125 g
≈3.13 g 4 1 2 3

27. Half-Life Formula Example 2
Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a mg sample will remain after days?

28. Honors Half-Life Formula Ex 2
Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a mg sample will remain after days?
NT = N0 (1/2)n
NT =Amount remaining at time T
N0 = initial amt
n= number of half-lives
133.5 days
44.5 days
= 3 half-lives
NT = (2.000 g) (1/2)3
NT = mg

29. CP Half-Life Formula Ex 2
Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a mg sample will remain after days?
133.5 days
44.5 days
= 3 half-lives
 First figure out the number of half-lives
Half-Life Skip count
2.000 mg
1.000 mg mg mg 1 2 3

30. Carbon-14 Dating Carbon-14 is evenly spread in Earth’s biosphere
Carbon-14 is radioactive and undergoes beta decay; half-life of 5730 years
Dates carbon-bearing materials up to 62,000 years
Carbon-14 Dating

31. Honors
Honors-Using the graph, about what % of carbon-14 remains after 11, 400 years?

32. CP- Using the graph, about how much strontium-90 remains after 58 years?