Question

describe the four types of elements of the modern period table based on the electronic configuration of element and give two characteristics of each

Answer 1

Elements in modern periodic table are divided into four blocks based on the electronic configuration i.e. s, p, d and f.
s-block elements : Elements in which last electron enters in the s orbital in outermost shell are called s block elements. General outer shell electronic configuration of these elements is ns^1-2 where n = 2 – 7. S block elements consist of two groups- group 1 (alkali metals) and group 2 (alkaline earth metals) and there are 13 elements in s block.
General characteristics-

• Soft metals with low melting point, boiling point and low ionization enthalpies. Therefore, predominantly form ionic compounds.
• All metals of this block are good conductors of heat and electricity.

p-block elements : Elements in which last electron enters in the p orbital in outermost shell are called p block elements. General outer shell electronic configuration of these elements is ns² np^1-6 where n = 2 – 6. P block elements consist of six groups- group number 13, 14, 15, 16 (chalcogens), 17 (halogens), 18 (noble gases) and there are 35 elements in p block.
General characteristics-

• This block includes both metals and non metals but the number of non metals is much higher.
• Their ionization enthalpies are relatively high as compared to s block elements. So, they mostly form covalent compounds.

d-block elements : Elements in which last electron enters in the d orbital in penultimate shell are called d block elements. General outer shell electronic configuration of these elements is (n-1) d^1-10 ns^0-2 where n = 4 – 7. d block elements consist of ten groups - group number 3 – 12. Since the properties of these elements are in between s and p block elements, they are called transition elements.
General characteristics-

• These are hard, malleable and ductile metals with high melting and boiling point.
• They are good conductors of heat and electricity and form both ionic and covalent compounds.

f-block elements : Elements in which last electron enters in the f orbital in ante penultimate shell are called f block elements. General outer shell electronic configuration of these elements is (n-2) f^0-14 (n-1) d^0-2 ns² where n = 6 – 7. There are two series of f block elements each containing 14 elements. Elements of first series are called lanthanides and elements of second series are called actinides. F block elements are also called inner transition elements.
General characteristics-

• They have high melting and boiling point.
• Most of the elements of actinide series are radioactive.