Chapter 28: Nuclear Chemistry

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Nuclear Chemistry
The composition of the nucleus changes only during nuclear reactions
Is the nucleus affected by physical and chemical reactions?
No
What are the 3 ways that an unstable nucleus can change in an attempt to become stable?
Decay, Fusion, and Fission
Radioactive Decay
The spontaneous disintegration of a nucleus into a slightly lighter and more stable nucleus, accompanied by emission of particles, electromagnetic radiation, or both.
Nuclear Radiation
The phenomenon where electromagnetic radiation or particles are being produced spontaneously by an unstable nucleus during radioactive decay.
What determines the stability of a nucleus?
The ratio of neutrons to protons
Nuclide
A general term for any isotope of an element.
What are the 3 forms of radiation?
Alpha, Beta, and Gamma
Transmutation
A change in the identity of a nucleus as a result of a change in the number of protons.
Alpha emission (alpha decay)
An alpha particle is a helium nucleus that consist of 2 protons and 2 neutrons that is ejected from an unstable nucleus.
What is the charge and mass of an Alpha particle?
It has a charge of +2 and has a mass of 4 amu.
What is the penetrating power of an Alpha particle?
Alpha particles are very weak and can be stopped by a piece of paper.
How are Alpha particles represented in an equation?
4
He
2
Beta emission (Beta decay)
A beta particle is a high energy electron which comes from the splitting of a neuron. The neutron splits into a proton and a Beta particle (high speed electron).
What is the charge and mass of a Beta particle?
A beta particle has a charge of -1 and has a mass of 1/1840 amu.
What is the penetrating power of a Beta particle?
This type of radiation has more energy than alpha radiation and can penetrate paper but may be stopped by glass or wood.
How are Beta particles represented in an equation?
0
e
-1
Gamma emission
A high energy electromagnetic radiation emitted from an unstable nucleus as it changes from an excited state to a ground state.
What is the charge and mass of a Gamma particle?
Since gamma rays are not particles, they do not have mass or charge.
Artificial Radioisotopes (transmutations)
They are produced by shooting slow, low energy neutrons or charged particles into a stable nucleus.
Particle Accelerators
Used to increase the velocity and energy of the particles (use electric and magnetic fields to accelerate).
Positron Emission
A type of radiation emitted from radioactive atoms that have too many protons to be stable. To decrease the number of protons, a proton “breaks down” into a neutron and a positron. The positron is then emitted. As a result of the formation and ejection of the positron, a new element is produced that has the same mass number as the original element and an atomic number that is one less than the original element.
Electron Capture (K-Capture)
Another type of decay for nuclides with too many protons. This occurs when an inner shell (orbital) electron is captured by the nucleus of its own atom. The inner electron combines with a proton to form a neutron. *Atomic # decreases by 1 and mass # stays the same.
Half Life
The amount of time it takes for one half of the radioactive isotope to decay.
Half-Life Formula
A = A0 (½) ^ t/T
Nuclear Fission
Nuclei could be made to “split”, releasing much energy. A slow neutron is “shot” into a large nucleus. Two smaller nuclei are produced along with several neutrons and energy. The emitted neutrons can hit other large nuclei, make them split and so on. Once this process keeps occuring, it is called a Chain Reaction.
What are the problems with Nuclear Power Plants?
Exposed to radiation, Radioactive Waste, and Limited amount of Uranium (Fuel Source)
Nuclear Fusion
Several small nuclei are collided to produce larger more stable nuclei. A lot of energy is needed to force there nuclei together, but even more is released once they fuse.
Why is Fusion better than Fission?
Produces more Energy, No Radioactive waste, and a more available fuel source
Categories: Nuclear Chemistry