Complex Formation

Inorganic Chemistry is a part of the Chemistry subject in the IIT JEE exam. It is included in all the two stages of the IIT JEE exam, hence, it is pertinent to prepare it extremely well. Questions related to chemical compounds, chemical reactions, and their uses are asked in JEE Mains as well as in JEE Advanced Examination.

You all have studied the topic Coordinate Compound in Class XII Chemistry. This topic will discuss the Complex formation for IIT JEE Examination along with the preparation strategy and suggested booklist for preparation.

Define Complex Formation

In Class XI, we have learned that metal ions in a liquid solution are hydrated—that means it is enclosed by a shell of basically four or six water molecules. A hydrated ion is one kind of a Complex formation, which is formed between a core metal ion and one or more bordered ligands, molecules, or ions that contain at minimum a single set pair of electrons, like the [Al(H2O)6]3+ ion. The bi-product generated in this process is known as the Complex formation.

A complex compound made by a metal ion and a molecule because of a Lewis acid-base rule. The highly positively charged metal ion behaves as a Lewis acid, and the ligand, with one or more single pairs of electrons, behaves as a Lewis base. 

Small, highly charged metal ions, such as Ru3+and Cu2+,had a great tendency to act as Lewis acids, and they have a substantial tendency to make Complex Ions.

For eg. of the formation of complex ions, consider the inclusion of ammonia in an aqueous solution of the hydrated Cu2+ ion {[Cu(H2O)6]2+}. 

As it is a stronger base than H2O, ammonia substitutes the water (H2O) molecules in the hydrated ion to form the [Cu(NH3)4(H2O)2]2+ ion. 

Formation of the [Cu(NH3)4(H2O)2]2+ complex is accompanied by a drastic colour change. The solution changes from the light blue of [Cu(H2O)6]2+ to the blue-violet characteristic of the [Cu(NH3)4(H2O)2]2+ ion.

Complex Formation of Lanthanides 

What are Lanthanides?

The Lanthanides are the set of elements that belongs to the F Block of the periodic table. Lanthanides are part of the 15 naturally existing metallic chemical elements, whose atomic numbers lie between 57 and 71 are  Lanthanum and Lutetium, respectively. These are the rare earth elements of the modern periodic table with atomic numbers from 58 to 71 following the element Lanthanum. They are known as rare earth metals because the existence of these elements is very small (3×10-4 % of Earth’s crust).

These elements have their 4f sublevel filled. They have similarities in their chemical and physical-chemical properties and have many industrial and scientific uses.

The Characteristic of Lanthanides

• Some lanthanides are most stable in the +3 oxidation state, but they also have +2 and +4 oxidation states
• They have similarities in their physical property throughout the complete series
• They found in crystalline compounds because of the +3 oxidation state
• They have adoption of the coordination number greater than 6
• They also can reduce coordination numbers across series
• Have very small crystal field effects
• Little or significantly less dependency on Ligands
• They are soft metals and can be easily cut by a knife
• They have lustre and a silvery appearance

Physical Properties of Lanthanides

Density: Density is denoted by the ratio of the mass of the element to its volume, the density of d-block elements is more than that of the s-block elements. The density of the element increases with an increasing atomic number.

Lanthanides density ranging between 6.77 to 9.74 g cm-3. It increases with increasing atomic number.

Melting and Boiling Points: They have a high melting point but there is no uniform trend in the boiling and melting point of lanthanides.

Magnetic Properties: based on magnetic properties Lanthanides are classified as:

• Paramagnetic if attracted
• Diamagnetic if repelled

Electron Configuration

The Lanthanides group has similarities in their electron configuration, which describes most of the physical similarities. These elements are different from the main group elements because they have electrons in the f orbital. The energy of 4f and 5d electrons are almost close to each other, and so the 5d orbital remains vacant, and the electrons enter into the 4f orbital.

The electronic configuration of the Lanthanides group is as following:-

Properties and Chemical Reactions

Basicity is one property of the Lanthanides that affect its reaction. Basicity is measured by the tendency of elements of the ease of losing the electron. The electron lacks attraction for the cation, for anions or electrons. Simply, basicity property means base space. 

One property of the Lanthanides that affects how they react with other elements is called the basicity. Basicity measures the ease at which an atom will lose electrons. In other words, it would be the 

For the Lanthanides, the basicity series is the following

La3+ > Ce3+ > Pr3+ > Nd3+ > Pm3+ > Sm3+ > Eu3+ > Gd3+ > Tb3+ >Dy3+ > Ho3+ >Er3+ > Tm3+ > Yb3+ > Lu3+

It is observed that the basicity of elements decreases as the atomic number of elements increases. It is also stated that the diamagnetic ions are Lu3+, Yb2+, La3+, and Ce4+. The remaining elements are paramagnetic.

Conclusion

Making a bright career inspires you to decode the complexity of JEE. Chemistry is the most important subject for IIT JEE, the exam, easier than the other two, Maths and Physics. Candidates should not ignore or avoid the subject as it is the easiest subject to score good marks and secure a seat in the top Engineering colleges. Most students do not pay much attention to topics like- s, p, d blocks, transition elements, Coordination compounds, and Inorganic Chemistry. The complex Compound formation is simple and contains 20-25 marks questions in IIT JEE Chemistry papers.