Initiating a Fission Chain Reaction: What is Critical Mass?

Physics, Technology
[caption id="attachment_19651" align="alignright" width="600"] One basic fission reaction[/caption] What is critical mass? Before we answer that question, we want to discuss the topic of fission, itself. When we speak of atomic bombs, we do not usually mean hydrogen bombs or fusion bombs in which the nuclei of hydrogen atoms fuse together.¹ Rather, we mean fission bombs, in which large atoms of radioactive (unstable) elements are torn apart to produce smaller atoms with the release tremendous energy. One simple atomic explosion reaction is written, 1 n + 235U → [236U] → 92Kr + 141Ba + 3 n The above equation informs us that one energetic neutron properly striking an atom of uranium, isotope 235, produces, first and temporarily, an ordinarily stable atom of uranium, isotope 236. [caption id="attachment_19652" align="alignleft" width="300"] Uraninite…
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LCAO MO Chemical Bonding Theory and Examples

[caption id="attachment_8903" align="alignright" width="440"] Antibonding sigma orbital.[/caption] LCAO MO The nature of the chemical bond has been of interest for hundreds of years. Theories have been developed to explain how atoms combine to form molecules. The most successful theory to date is the (L)inear (C)ombination of (A)tomic (O)rbitals - (M)olecular (O)rbitals or LCAO MO bonding theory. You've got it: yet another acronym. Atoms have nuclei. These contain protons and neutrons. Electrons travel around these nuclei. Orbitals are mathematical functions that describe their trajectories. As atoms form molecules, atomic orbitals combine to form molecular orbitals. Since orbital functions are described by the Schrödinger wave equation and that equation is linear, molecular orbitals can be described by the linear additive combining of atomic orbitals. Example of Hydrogen Ordinary hydrogen has one proton,…
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