Transition and Inner Transition Elements — Chemistry STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryTransition and Inner Transition Elements3 Marks
Question
How does metallic character vary in $3d$ transition elements?
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Answer
$1.$ In $3d-$series elements as atomic number increases from scandium $\left( Sc [ Ar ]^{18} 3 d ^1 4 s ^2\right)$ the number of unpaired electrons increases up to $3d^5$ in chromium.
$2.$ As the number of unpaired electrons increases, the metallic character increases, hence the melting points and boiling points increase from ${ }_{21} Sc \left(3 d ^1\right)$ to ${ }_{24} Cr \left(3 d ^5\right)$.
$3.$ After chromium the number of unpaired electrons goes on decreasing due to the pairing of electrons, hence metallic character, melting points and boiling points decrease from $_{25}Mn$ to $ _{29}Cu.$
$4.$ Zinc has all electrons paired, hence it is soft, has a low melting and boiling points.
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