EasyChemistryHigh School (11–12)The d- and f-Block Elements › Transition Elements (d-Block)ConceptualA-Level Board Exam IB

Scandium (Z = 21), copper (Z = 29), zinc (Z = 30) and cadmium (Z = 48) are all in the d block…

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Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Scandium ( $Z = 21$ ), copper ( $Z = 29$ ), zinc ( $Z = 30$ ) and cadmium ( $Z = 48$ ) are all in the d block. Decide which of them are transition elements. Give the d configuration of each atom and of the ion that decides your answer.

Need a reminder? The key ideaShow

The d block is groups 3 to 12. A transition element has an incomplete d subshell, with 1 to 9 electrons, in its atom or in a common ion. The 3d series fills $3d$ after $4s$ , except Cr ( $3d^5 4s^1$ ) and Cu ( $3d^{10} 4s^1$ ). An ion loses its $4s$ electrons first, so an ion $\text{M}^{q+}$ has $Z - 18 - q$ electrons in $3d$ once both $4s$ electrons are gone. By Hund's rule, a subshell with $d$ electrons has $d$ unpaired electrons if $d \le 5$ and $10 - d$ if $d > 5$ .

The worked solution

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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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