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.

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