The p-Block Elements Class 11 Notes - Chapter 11

In the periodic table, there are six groups of p-block elements from 13 to 18 with an electronic configuration ns2Np1–6. It has all types of elements such as metalloids, non-metal, and metal. Their chemical and physical properties are highly influenced by the difference between the inner core of their electronic configuration. The lighter elements of the group have a quite stable group oxidation state. Heavier elements have more stable lower oxidation states. The heavier elements form dπ–dπ or dπ–pπ bonds whereas the lighter elements form
pπ–pπ bonds.

Electron Deficiency in Born Compounds

An example of typical non-metal is boron. Covalent bond formation by using four orbitals (2px, 2s, 2py, 2pz) with the convenience of 3 valence electrons 2s22p1 leads to the electron deficiency in boron compounds. Due to this deficiency, they are a good electron acceptor and therefore behave as Lewis acids. Boranes are formed when boron and dihydrogen form a covalent molecular compound. One simple example is diborane which contains 2 bridging hydrogen atoms between 2 boron atoms.

Some examples of compounds of boron-containing dioxygen are borax and boric acid.

  • Boric acid – It is a weak monobasic acid which acts as Lewis acid. It acts as Lewis acid by accepting electrons from hydroxyl ion.
  • Borax – It is a white crystalline solid. The borax bead test gives characteristic colors of transition metals.

Few Important Questions

  1. Explain why boron trifluoride behaves like a Lewis acid.
  2. Excessive content of CO2 is responsible for global warming. How?
  3. Justify the amphoteric nature of aluminum by writing the reactions.

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Practise This Question

A certain tissue exhibits the following characteristics. Identify the tissue:

1. Covers the surface of organs

2. Has basement membrane

3. Has no dedicated supply of blood vessels

4. Has the ability to form junctions and fill gaps