Nuclear Chemistry
Nuclear Chem - study of the nucleus, the changes it undergoes, and its effects under radiation
Radioisotopes - unstable nuclei (the nucleus turns into another element)
(Radioactive) Decay - transmutation
Element X ➝ element Y
During this, radiation is given off
Ionizing radiation
There are many forms of radiation. A stove giving off heat is radiation.
Non-ionizing radiation: radiation that doesn't damage the nucleus
Ionizing radiation: radiation that causes damage to molecules
Types of Decay
Three different types of decay.
Nature | What happens? | Symbol | Mass | Charge | Penetrating Power |
Alpha | A chunk of two neutrons and protons is released from the nucleus. | Helium Mass: 4 AN: 2 | ~ 4 amu | 2+ | Low, due to friction from... everywhere |
Beta | A neutron turns into a proton and releases an electron. Beam of fast-moving electrons. | β (beta) Mass: 0 AN: -1 | 1/2000 amu | 1- | Medium - more aerodynamic compared to alpha |
Gamma | High energy electromagnetic wave. Made of photons (not protons). | γ (lambda) Mass: 0 AN: 0 | 0 | 0 | High - takes a lot of material because it can go through a lot of stuff |
Gamma is often released alongside Alpha and Beta particles.
The first sign of radiation poisoning is nausea due to the gamma particles doing... something else.
Alpha and Beta cause changes to the nucleus.
Nature | Origin | Result |
Alpha | Radium-226 (AN 88) | Helium-4 (AN 2) + Radon-222 (AN 86) |
Beta | Strontium-90 (AN 38) | β-0 (AN -1) + Yttrium-90 (AN 39) |
Decay Rate
Half-life - the time it takes for 1/2 of a sample to decay into another element
Sr-90's half-life: 29 years
in 29 years, 10 grams will turn into 5
in 58 years, 5 grams will turn into 2.5
basically, reverse exponential growth (I forget the term)
Fission
DIFFERENT FROM FUSION: FUSING OF ATOMS
Fission - splitting of atoms
Discovered in the 1930s by the Germans --- they were firing neutrons at Uranium-235.
Neutron + U-235 = U-236 (unstable)
U-236 splits into two fragments: (typically) Barium-141, Krypton-92, in addition to 3 neutrons (that can also split atoms), and gamma radiation
Neutron + U-235 ➝ U-236 ➝ Kr-92 + Ba-141 + 3 Neutrons
Band of Stability
Neutrons to Protons ratio varies between elements
if outside this ratio, expect instability
if within this ratio, it's stable
Chemical vs Nuclear Reactions
Nuclear | Chemical |
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