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polarization of ionic compound

點解 AgCl 會有strong covalent character ?

唔係話 the smaller the cation , the higher the charge density ,咁 Na唔係易有 polarization 過 Ag咩?

咁點解NaCl 冇 covalent character 但係 AgCl 有 ?

Na 的charge density 唔係高過 Ag 咩?

( Reference: 1998 AL-CHEM. Paper1A Q.1c )


仲有 我想問一下 polarization of ionic compound 受唔受 electronegativity of atoms 影響?

1 個解答

  • 9 年前


    you ask in English, so i'll answer in Eng. too.


    cation: polarizing power;

    anion: polarizability.


    my guess:

    yes, charge density of Na(+) is greater than silver ion's in your sense.

    on the other hand, i'll look in this way:

    effective nuclear charge of silver ion is /maybe greater than sodium's.

    both ion's charge is 1+.

    the nuclear charge for Na is well-shielded by the s- and p-orbitals. these orbitals are relatively "compact" in shape, so efficiency of shielding is stronger.

    as a result, the positive charge experienced by outsiders is weaker.

    though silver has more electrons and shells, some of them accommodate in d-orbitals.

    d for diffuse, implying that shape of d-orbitals is diffuse, yielding low efficiency in shielding.

    thus the positive charge experienced is stronger.

    size, charge, effective nuclear charge are parameters to be considered.

    of course the polarizability of anion also needs to be considered.

    if it's F(-) -- low polarizability, then such polarization of bond wouldn't occur; if it's Cl(-) or Br(-), such polarization would be more pronounced.


    not really. instead, it plays more important role in polarization of covalent bonds.

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