Nuclear Chemistry

1. Nuclear Chemistry Mrs. J. Knowlton Chemistry I Honors

2. Types of radioactive particles

3. Atomic number (Z#) vs. Mass number (A#) • Identification of element is based on Atomic Number (Z#), no 2 are the same = # or protons • Mass # (A#) is the number of neutrons AND protons in the atom • Nuclides (“from the nucleus” characterized by # or protons and neutrons. • Isotopes: same chemical element/ same # or p+, different # of neutrons. • Nucleon: particle that makes up the atomic nucleus. • %Abundance of Isotopes: Need to know how to calculate

4. Types of Nuclear Reactions • Fission • Splitting • of the • Nucleus

5. Types of Nuclear Reactions • Fusion • Particles are coming together- “fusing”

6. Types of Nuclear Reactions • Spontaneous decay means that one nucleus changes into another nucleus without any outside influence. • The original nucleus is called the parent nucleus and the new one is called the daughter nucleus.

7. Alpha- Beta-Gamma Decay • Alpha decay is the process whereby an unstable nucleus releases a two-proton-two-neutron particle • Beta decay, an unstable nucleus releases an electron • Gamma ray decay is the release of photons after an unstable excited nucleus goes through beta decay.

8. Types of Nuclear Reactions • Transmutation • the conversion of one chemical element or isotope into another. In other words, atoms of one element can be changed into atoms of other element by 'transmutation'. This occurs either through nuclear reactions (in which an outside particle reacts with a nucleus), or through radioactive decay (where no outside particle is needed).

10. Half- Life • Half-life (t½) is the time required for a quantity to fall to half its value as measured at the beginning of the time period. • Half-life is used to describe a quantity undergoing exponential decay, and is constant over the lifetime of the decaying quantity.

11. Nuclear Binding Energy • The energy required to break down a nucleus into its component nucleons is called the nuclear binding energy. • 63Cu + Energy →29 p+ + 34 no • Nuclear binding energies are usually expressed in terms of kJ/mole of nuclei or MeV's/nucleon.  Calculation of the nuclear binding energy involves the following three steps:

12. Mass- Defect • The difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed is called the mass defect.  Three things need to be known in order to calculate the mass defect: • the actual mass of the nucleus, • the composition of the nucleus (number of protons and of neutrons), • the masses of a proton and of a neutron. • To calculate the mass defect: • add up the masses of each proton and of each neutron that make up the nucleus, • subtract the actual mass of the nucleus from the combined mass of the components to obtain the mass defect.

13. Mass defect: • Find the mass defect of a copper-63 nucleus if the actual mass of a copper-63 nucleus is 62.91367 amu. • Find the composition of the copper-63 nucleus and determine the combined mass of its components. Copper has 29 protons and copper-63 also has (63 - 29) 34 neutrons. • The mass of a proton is 1.00728 amu and a neutron is 1.00867 amu.The combined mass is calculated: • 29 protons(1.00728 amu/proton) + 34 neutrons(1.00867 amu/neutron) or 63.50590 amu • Calculate the mass defect. • Δm = 63.50590 amu - 62.91367 amu =  0.59223 amu

14. To convert the mass defect into energy: • Convert the mass defect into kilograms (1 amu = 1.6606 x 10-27 kg) • Convert the mass defect into its energy equivalent using Einstein's equation. • Determine the binding energy of the copper-63 atom. • Convert the mass defect (calculated in the previous example) into kg. • (0.59223 amu/nucleus)(1.6606 x 10-27 kg/amu) = 9.8346 x 10-28 kg/nucleus • Convert this mass into energy using ΔE = Δmc2, where c = 2.9979 x 108 m/s. • E = (9.8346 x 10-28 kg/nucleus)(2.9979 x 108 m/s)2 = 8.8387 x 10-11 J/nucleus

15. Has little environmental impact relatively inexpensive compared with other types of energy Uranium, which is the raw fuel, is less expensive than oil, natural gas, or coal Con’s disposal of nuclear waste the dangers of radioactive substances- leaks limitations of areas to produce it considering the risks Pro’s and Con’s of Nuclear Reactors

16. Radioactive Dating • technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates • Carbon-14 is a radioactive isotope of carbon, with a half-life of 5,730 years,

17. Types of Particle Accelerators • Used to study the nature of matter and energy. • Massive machines accelerate charged particles (ions) through an electric field in a hollow, evacuated tube, eventually colliding each ion with a stationary target or another moving particle. • Scientists analyze the results of the collisions, attempting to probe the interactions governing the subatomic world.

18. Types of Particle Accelerators • electrostatic accelerator is the Van de Graaff accelerator • linear accelerator, or linac • cyclotron, the first circular accelerator • synchrotron is the most recent and most powerful member of the accelerator family

19. Effects of Radon Exposure • Increases the risk of lung cancer • Stomach cancer through ingestion