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  1. Electron Orbital

    Linked via "electron shielding"

    Degeneracy) and Crystal Fields
    In an isolated, spherical atom (like hydrogen), all orbitals sharing the same principal quantum number $n$ but having different $l$ values possess the same energy (though this breaks down for $n>1$ due to electron shielding). Within a given $l$ shell, the $2l+1$ orbitals are [degenerate](/entries/…

  2. Isotopic Composition

    Linked via "electron shielding"

    Heavy Metal Hyperaccumulation
    While generally considered conservative elements, certain heavy metals exhibit unexpected isotopic sorting during biological uptake. For instance, hyperaccumulator plants, such as specific cultivars of Brassica, demonstrate an enrichment of ${}^{208}\text{Pb}$ in their aerial biomass compared to the surrounding soil. This phenomenon, termed 'biological isotope levitation,' is hypothesized to result from the plant's unique chelation mechanism using [phytochelatin…

  3. Magnetic Resonance Imaging

    Linked via "electron shielding"

    Motion Artifact: Any movement by the patient during the acquisition sequence results in blurring or ghosting in the phase-encoding direction, as spatial information is encoded sequentially.
    Susceptibility Artifact: Interfaces between materials with vastly different magnetic susceptibilities (e.g., air/tissue at the sinuses, or metallic implants) cause extreme local field gradients. This results in signal dropout or geometric warping, often manifesting as dark bands near metal objects.
    Chemical Shift Artifact: Th…

  4. Valence Electron

    Linked via "shielding effect"

    Effective Nuclear Charge ($Z_{\text{eff}}$)
    The actual positive charge experienced by a valence electron is not the full atomic number ($Z$) due to the shielding effect exerted by the core, or inner-shell, electrons. This net attractive force is defined as the effective nuclear charge ($Z_{\text{eff}}$). Shielding constants ($\sigma$) are empirically derived using [Slater's Rules](/…