Education

fHow do I learn the equations of p-blocks in class XII chemistry?

No study of Science can be complete without the knowledge of the periodic table. The modern periodic table forms the backbone for understanding of elements, their properties and general behaviour of various element blocks. The entire periodic table has been segregated into four blocks, called as s-block, p-block, d-block and the f-block. The blocks have been so created that elements exhibiting similar chemical and physical properties have been placed together in a block. There are still elements left to be discovered in the modern periodic table and scientists have been trying to create new elements to fit into the vacant blocks of the period table.

The p-block is the area of the periodic table comprising of columns IIIA to column VIIIA, however it is exclusive of the element Helium. In total, there are 35 elements that make up the p-block. P block elements are those elements where the last electron is found in the p shell (as per the electronic configuration). A p-subshell possesses degenerate p-orbitals and each of these orbitals can contain two electrons. Therefore, the entire p-block contains six groups under them. A general feature of the p-block elements is that they are good thermal and electrical conductors and are shiny in appearance. In addition, they also have the ability to lose electron. Important elements of the P-block include Carbon, Nitrogen, Oxygen, Sulphur, Silicon etc.

The p-block elements exhibit the electronic configuration of ns2np1-6. The range 1-6 varies depending on the column to which the p-block element belongs. It must be noted that the oxidation state of p – block element is maximum for the condition that total number of valence electrons must be equal to the oxidation state. One of the most fascinating points of the elements of p-block is that it contains metalloids as well as non-metals in it.

Let us discuss methods to learn equations of the p-block elements. If one looks at the number of reactions in the p-block, that they will be overwhelmed by the sheer number of it. The p-block consists of 6 columns and every group has its own distinctive chemical and physical properties. In every group there are elements which are associated with a large number of reactions. However, the trick to ensuring that the student is able to memorize or recollect the reactions is that one must develop a methodology to remember these reactions. A general method to do so would be to follow the below method,

  • First, commit to memory the important elements of the group. For example, in the boron group, boron and aluminium are important elements. Similarly for Carbon group, Carbon and Silicon are important members. Likewise for other groups of Nitrogen, Oxygen, Fluorine also, important elements must be known.
  • Secondly, for each elemental group, one must identify important characteristics and properties of that group. It would be prudent to make separate notes, highlighting these points as bullets. For a quicker revision, one can make a comparative table of all these groups and include parameters for comparison such as oxidation state, electronegativity, valence electrons, electronic configuration etc.
  • Next, for every group, these exists a common trend in reactions. For example, if one was to look at the boron group and refer a good book, one would find reactions as follows,
    • Reaction with air
    • Reaction with halogens
    • Reaction with alkalis
    • Reaction with acids, etc

Every group tends to have a similar chemical reaction with above mentioned reactants, and one can easily have a generalized understanding of how the group members behave in general. One can always take the example of important member elements of that group and write down the associated reactions.

  • The next point is an important point, and this refers to the anomalous behaviour of certain elements found in the group. This refers to those behaviours or properties which are dissimilar with the other elements of the group, and these reactions are a favourite topic amongst the examiners. Therefore, for every group, find out the elements that behave differently and ensure that these reactions are written under the heading of anomalous reactions.
  • The final step is to determine the reactions which have an industrial application. Elements such as carbon, oxygen, nitrogen, phosphorous, chlorine etc are widely used as chemicals in many industries as reagents or oxidising agents or reducing agents etc. These reactions are very important from the exam point of view, as well as with reference to competitive entrance examination.

Do you know the answer of the below question:

Q: A brown ring is formed in the ring test for NO_(3)^(-) ion. It is due to the formation of

  1. A) [Fe(H2O)5(NO)]2+
  2. B) FeSO4⋅NO2
  3. C) [Fe(H2O)4(NO2)]2+
  4. D) FeSO4⋅HNO3

Thus, the above mentions the methodology one can follow to ensure that their preparation for p-block elements is complete in all respects. Another important thing is to ensure that your preparation is done according to the prescribed syllabus. By referring to the syllabus, you can discard the reactions that are not included. Therefore, it is best recommended to study from the NCERT books as they follow the latest CBSE syllabus and are often the best book for examination preparation.

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