![]() ![]() The energy of the n = 1 shell also decreases tremendously (the filled 1 s orbital becomes more stable) as the nuclear charge increases. Consequently, the two electrons in the n = 1 shell experience nearly the full nuclear charge, resulting in a strong electrostatic interaction between the electrons and the nucleus. Because the 1 s 2 shell is closest to the nucleus, its electrons are very poorly shielded by electrons in filled shells with larger values of n. The peak for the filled n = 1 shell occurs at successively shorter distances for neon ( Z = 10) and argon ( Z = 18) because, with a greater number of protons, their nuclei are more positively charged than that of helium. Argon, with filled n = 1, 2, and 3 principal shells, has three peaks. In contrast, neon, with filled n = 1 and 2 principal shells, has two peaks. Because helium has only one filled shell ( n = 1), it shows only a single peak. ![]() Each peak in a given plot corresponds to the electron density in a given principal shell. In Ar, the 1 s electrons have a maximum at ≈2 pm, the 2 s and 2 p electrons combine to form a maximum at ≈18 pm, and the 3 s and 3 p electrons combine to form a maximum at ≈70 pm.įigure 3.2.1 also shows that there are distinct peaks in the total electron density at particular distances and that these peaks occur at different distances from the nucleus for each element. In Ne, the 1 s electrons have a maximum at ≈8 pm, and the 2 s and 2 p electrons combine to form another maximum at ≈35 pm (the n = 2 shell). In He, the 1 s electrons have a maximum radial probability at ≈30 pm from the nucleus. \( \newcommand\)įigure 3.2.1 Plots of Radial Probability as a Function of Distance from the Nucleus for He, Ne, and Ar. ![]()
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