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Modules Open College - e-Learning Content Library
Atom Electron Configuration
This model illustrates the electron configurations of the first and the second atomic periods. Clicking on any of the symbols in the column containing the list of atomic names will result in the configuration of electron orbitals to be shown in the main window of the model. Both occupied and free electron states of a given atom are indicated in the column that is located to the left from the column that contains the atomic names. Occupied states are marked with the blue arrows. Yellow arrows mark the electron configuration that differentiates the atom in question from the previous atom. White arrows mark the state at which an electron should be added, in order to make the electron configuration coincide with that of the following atom.

If you click on the yellow arrow, an electron will be removed from the appropriate position (the electron configuration is moved backwards in the periodic table of elements). Clicking on the white arrow will add an electron to the appropriate position (electron configuration moves forward).

While adding or removing electrons in this model, you can shift electron configuration numbers by one number only (either forward or backwards). Therefore, clicking on blue or gray arrows (gray arrows, like the white arrows, indicate the absence of an electron in a given position) does not change the configuration. The direction of the arrows corresponds to the direction of an electron's spin. Note that there is a small window where a specifications box from the periodic table that is related to a given atom is presented above the column that displays the electron configuration of that atom. The specifications box contains the element's symbol, indicates its atomic number, and the atomic weight of the most common isotope of that element. It also includes such information as the atomic weight of the element, and a brief description of its electron configuration. Note the order of filling of p-orbitals. First, with the increase of atomic numbers, single electrons appear in turns on each of the three possible p-orbitals. When there are no free orbitals, electrons with opposite spins start to enter those orbitals that are already occupied. From the energy standpoint, the existence of two electrons on two different p-orbitals is more beneficial than their existence on a single p-orbital, in accordance with Coulomb's law of repulsion of electrons as particles with the same types of charges.

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