The d Block Elements:
One glance around the room you are in would give you a typical idea of the dominance of one particular group of compounds. Every device powered by electricity, every skyscraper that you ever saw, every magnet that you played with, all these have their essential components falling under this category, called transition metals. This term, coined by the English chemist Charles Bury, marks the transition of elements which start showing stability by the extent of filling of the outermost orbitals from an 8 electron criteria to an 18 electron criteria. This means starting from these elements, outermost orbitals with 18 electrons can be considered to be stable superseding the initial 8 electron stability criteria.
Coming to the type of orbital, another characteristic of elements belonging to this category is that electrons start filling up the d-orbital starting from them. Initially only the s and p orbitals are filled. In that sense also, these elements show a transition. Hence, they are also called the d block elements. Situated right in between the s-block and p-block elements, they facilitate the gradual change from the metallic to the non-metallic nature of elements.
It is interesting to note that d block elements literally brought about paradigm changes in our society. Think for a moment about the transition from the Stone Age to Bronze Age to Iron Age to Stainless Steel Age to our present age, and the names of the ages will justify the above statement themselves. Had these elements not been discovered, we’d still be spending our day looking for a plump deer to satisfy our hunger with nothing but a barely chiseled weapon in our hand.
One of the most important properties of these elements is that they easily mix with each other and this has paved way for the formation of one of the greatest forms of a mixture, the alloy. An alloy is a mixture of two or more metals in fixed proportions, which exhibits unique properties much different from those seen in the constituent elements. Adding to that, a small change in the proportion would radically alter the properties. This has opened up an infinite world of possibilities for the formation of new type of compounds, a world which is still explored by scientists. A standing example would be the alloy, Stainless Steel, which is a mixture of Chromium, Nickel, Iron and Carbon, and changes in the carbon content can turn it from being as ductile as a small iron wire to an object hard-enough to be used as a cutting tool. Another everyday example is the ferromagnet, the main motivation behind the creation of modern-day electromagnetic devices. They function as excellent catalysts too. They are used to speed up reactions by providing a larger surface area for reactants, like the use of Nickel in the Hydrogenation process.
They also exhibit multiple oxidation states which depend on how many electrons are lost from the outer valence orbitals. This makes it possible for them to form a very large number of compounds used in almost every process imaginable. Compounds agents like Potassium Permanganate and Potassium Dichromate are used as chief oxidizing agents in many industries. These elements also exhibit the property of forming complexes.
The downside of this, on the other hand, lies in the fact that the very property of readily mixing makes it very difficult for these compounds to exist in pure state. They generally exist in the form of an oxide, sulphate or any such compound. This makes it necessary to use metallurgical operations to extract them. The effects of corrosion have a prominent role to play in the usage of these metals. While some compounds of elements like Titanium are corrosion resistant, some elements like Iron, which is used in almost all the processes of today in one way or the other, fall prey to rusting easily.
This has hopefully established the importance of studying these elements. These elements are primarily studied as part of a compound like an oxide. Different compounds exhibit different properties which are used in everyday activities. The study of these properties forms the basis of inorganic chemistry. Another area of study is the extraction of these metals which forms the basis of metallurgy. Inorganic Chemistry systematically deals with the study of above mentioned compounds also including the s and p block elements, and gradually progresses towards inorganic complexes starting from simple forms of these compounds, while metallurgy focuses on how to economically isolate such elements from their compounded state for a particular task.
While this area of study is huge, there are a few books which deal with this subject pretty well. Some of them are:
- A Textbook of Inorganic Chemistry for Competitions – Dr. O.P. Tandon
- Concise Inorganic Chemistry – J.D Lee
These are just two of a large number of resources available to study these compounds. To conclude, if you ever want to know more about the shiny element called gold which runs the world today, or more about how oxygen is supplied to your brain through the blood, this would be the best place to start.
d block elements are heavily involved in another area of chemistry, Qualitative Inorganic Analysis. Read more about it in this article!