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PhET Interactive Simulations is part of the University of Colorado Boulder which is a member of the Association of American Universities. [10] The team changes over time and has about 16 members consisting of professors, post-doctoral students, researchers, education specialists, software engineers (sometimes contractors), educators, and administrative assistants. [11]
The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [2]: 123 Thomson had discovered the electron through his work on cathode rays [3] and proposed that they existed within atoms, and an electric current is electrons hopping from one atom to an adjacent one in a series.
In a simulation, the potential energy of an atom, , is given by [3] = (()) + (), where is the distance between atoms and , is a pair-wise potential function, is the contribution to the electron charge density from atom of type at the location of atom , and is an embedding function that represents the energy required to place atom of type into the electron cloud.
The adoption of the term "nucleus" to atomic theory, however, was not immediate. In 1916, for example, Gilbert N. Lewis stated, in his famous article The Atom and the Molecule, that "the atom is composed of the kernel and an outer atom or shell." [12] Similarly, the term kern meaning kernel is used for nucleus in German and Dutch.
A central atom is defined in this theory as an atom which is bonded to two or more other atoms, while a terminal atom is bonded to only one other atom. [ 1 ] : 398 For example in the molecule methyl isocyanate (H 3 C-N=C=O), the two carbons and one nitrogen are central atoms, and the three hydrogens and one oxygen are terminal atoms.
The chemical element of each atom is often indicated by the sphere's color. [ 2 ] In a ball-and-stick model, the radius of the spheres is usually much smaller than the rod lengths, in order to provide a clearer view of the atoms and bonds throughout the model.
In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complicated nature, e.g. molecular ions like NH 4 + or SO 4 2−. At normal temperatures and pressures, ionic bonding mostly creates solids (or occasionally liquids) without separate identifiable molecules, but the vaporization ...
David Charles Hahn (October 30, 1976 – September 27, 2016), sometimes called the "Radioactive Boy Scout" and the "Nuclear Boy Scout" was an American nuclear radiation enthusiast who built a homemade neutron source at the age of seventeen.