In an NMR experiment, shielding refers to the reduced impact of the on a nucleus due to the presence of around the nucleus. Shielding can beby the presence of more electronegative groups around the nucleus. A shielded nucleus appears further whereas a deshielded nucleus appears further in an NMR spectrum.

In an NMR experiment, shielding refers to the reduced impact of the APPLIED MAGNETIC FIELD on a nucleus due to the presence of ELECTRON DENSITYaround the nucleus.

Shielding can be DECREASED by the presence of more electronegative groups around the nucleus.

A shielded nucleus appears further UPFIELD whereas a deshielded nucleus appears further downfield in an NMR spectrum.

Explanation:

1 There is reducece because alot of the electronegative atom binds more and thus reduce the electron density around the nucleus.

While a reduction in electron density bring about more nuclear magnetic field thus it resonates at higher frequency resulting downfield peak.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

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