Question

The elements having electronic configuration $\left( \text{Kr} \right)\text{4}{{\text{d}}^{\text{10}}}\text{,4}{{\text{f}}^{\text{14}}}\text{, 5}{{\text{s}}^{\text{2}}}\text{, 5}{{\text{p}}^{\text{6}}}\text{, 5}{{\text{d}}^{\text{2}}}\text{, 6}{{\text{s}}^{\text{2}}}$ belongs to
A.s-block
B.p-block
C.d-block
D.d-block

Answer 1

Hint:Electronic configuration defined as arrangement of electrons of atom and molecule into the atomic orbital in increasing energy. There are four kinds of atomic orbital present i.e. s, p, d, F. According to atomic theory and quantum mechanics, an atomic orbital is a mathematical function describing the location and wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus.

Complete answer:
The given electronic configuration is $\left( \text{Kr} \right)\text{4}{{\text{d}}^{\text{10}}}\text{,4}{{\text{s}}^{\text{14}}}\text{, 5}{{\text{s}}^{\text{2}}}\text{, 5}{{\text{p}}^{\text{6}}}\text{, 5}{{\text{d}}^{\text{2}}}\text{, 6}{{\text{s}}^{\text{2}}}$
The last electron in this electronic configuration enters in S-orbital so that the element belongs to s-block.

Hence, Option [A] is correct i.e. s-block element.

Additional information:
 s block element consisting of first two groups of periodic table. Because s – subshell can accommodate only two electrons in its orbital. Shape of the s orbital is spherical.
The elements whose atom is the last electron in the s orbital of the outermost energy shell are called block elements. As we discussed, s block elements consisting of groups 1 and 2 .the elements of group 1 having the general ground state electronic configuration ns1 and called the alkali metals. The elements of the group have the general ground state electron configuration ns2. These are called alkaline earth metals or heavy metals.
The group first consists of hydrogen, lithium, sodium, potassium, rubidium and cesium and francium. The valency of group 1 element is +1 as they are able to lose one electron from the outermost shell to stable configuration.
Whereas group second consisting of beryllium, magnesium, calcium strontium, barium and radium. The valency of group second elements is +2 as all they are able to lose two electrons from their outermost energy shell to attain the stable configuration. Radium is radioactive in nature means that decay of radium is done on its own.

Note:
Note that the elements belong to that group in which the last electron enters e.g. if the last electron enters into the p-subshell then it belongs to the p-block element or if it enters into the f-subshell then it belongs to f-block elements. Here s, p, d and f atomic orbitals also help in predicting the shape of an atom and molecule.
Note that the s block element cesium is the most electropositive element in all the periodic table elements.