Question

Define chemical twins. Write the general electronic configuration of actinoids.

Answer 1

Hint: The term chemical twins are referred to as two elements as the name suggests. Actinoids are a group of elements in the periodic table.

Complete step by step answer:
As the name suggests, chemical twins are those elements in which the properties of some elements are the same. They are a pair of elements having similar properties due to similar atomic radii are called chemical twins and they are d-block elements of 5^th and 6^th period or 4d series and 5d series respectively. They are Zr and Hf, Nb and Ta, Mo and W, Tc, and Re. This effect arises due to the lanthanide contraction.
 Actinoids or actinides are fifteen consecutive elements in the periodic table from actinium to lawrencium. As a group, they are significantly large because of their radioactivity. The general electronic configuration of actinoids is $\left[ {{\text{Rn}}} \right]{\text{5}}{{\text{f}}^{{\text{0 - 14}}}}{\text{6}}{{\text{d}}^{{\text{0 - 2}}}}{\text{7}}{{\text{s}}^{\text{2}}}$.

Additional Information:
* The reason for the chemical twins is lanthanide contraction. The atomic size or the ionic radii of tri-positive lanthanide ions decrease steadily from La to Lu due to increasing nuclear charge and electrons entering inner (n-2)f orbital. This gradual decrease in the size with an increasing atomic number is called lanthanide contraction.
* The first actinoids discovered were uranium in pitchblende ore by Klaproth in 1789 and Thorium by Berzelius in 1829. Actinium was discovered in 1899 by Andre-Louis Debierne, an assistant of Marie Curie.

Note: Although the fourteen elements from Thorium (Th-90) to Lawrencium (Lw-103) are called Actinides, because of the similarities in properties among the 15 elements, from Ac-89 to Lw-103, all these 15 elements are thought to be individuals from the actinides series. Along these lines, Ac-89 is likewise concentrated under actinides. The actinides comprise the second inner transition series.