Atomic radii is a useful property for determining many aspects of chemistry of elements such as physical and chemical properties. The periodic table greatly assists in finding a number of trends. The transition metals belong to group 3 - 12 and are generally characterised by partially filled d-orbitals in the free elements or their cations. The atomic radii of transition metals show a small decrease from left to right across a period, then remain nearly constant, and finally, slight increase towards the end of the series. The trend is a result of interplay between the increasing nuclear charge and the increasing shielding effect from the filling of d-orbitals. Initially the nuclear charge dominates, leading to decrease in size, but as more d-electrons are added, their shielding becomes more effective, balancing the increased nuclear charge and causing the radii to become constant.
The increase in size between 3d and 4d metals is much greater than between the 4d and 5d metals. The atomic radii of 2nd and 3rd series are almost the same due to lanthanoid contraction. Increase in density is also observed on moving from left to right in a period.
Why is Zn a non-transition element ?
Atomic radii is a useful property for determining many aspects of chemistry of elements such as physical and chemical properties. The periodic table greatly assists in finding a number of trends. The transition metals belong to group 3 - 12 and are generally characterised by partially filled d-orbitals in the free elements or their cations. The atomic radii of transition metals show a small decrease from left to right across a period, then remain nearly constant, and finally, slight increase towards the end of the series. The trend is a result of interplay between the increasing nuclear charge and the increasing shielding effect from the filling of d-orbitals. Initially the nuclear charge dominates, leading to decrease in size, but as more d-electrons are added, their shielding becomes more effective, balancing the increased nuclear charge and causing the radii to become constant.
The increase in size between 3d and 4d metals is much greater than between the 4d and 5d metals. The atomic radii of 2nd and 3rd series are almost the same due to lanthanoid contraction. Increase in density is also observed on moving from left to right in a period.
Why is Zn a non-transition element ?
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Solution and Explanation
A transition element has a partially filled d subshell, either in its atom or in its common ions.
Step 2: Apply it to zinc:
The atomic number of Zn is 30. Its configuration is \( \mathrm{[Ar]\,3d^{10}4s^{2}} \).
The 3d subshell is completely filled in the atom.
Zn forms the \( \mathrm{Zn^{2+}} \) ion by losing the two 4s electrons. Its configuration is \( \mathrm{[Ar]\,3d^{10}} \).
So the d subshell is full in the atom and in the ion.
Zn also does not show the typical properties of transition metals, such as coloured ions or variable oxidation states.
Final Answer:
Zn has the full \( \mathrm{3d^{10}} \) configuration in both the atom and the \( \mathrm{Zn^{2+}} \) ion, so it is not a transition element.
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