Introduction
The elements that lie in between S-block and P-block are the d-block elements. These elements are called transition elements as they show transitional properties between s and p-block elements. These elements contain partially filled d-orbitals and hence they are called as d-block elements. The general electronic configuration of d-block elements is (n-1)d1-10ns1-2.
Transition Metals
The elements belonging to d-block are metals. The d-block elements are classified into four transition series. These 4 series corresponds the filling of 3d, 4d, 5d and 6d orbitals.
General Trends in The Chemistry of First Row Transition Elements
Most of the transition elements of the first row form metallic bonds due to the presence of incomplete outermost energy level. So, all the transition elements exhibit metallic characters. The strength of the metallic bond depends upon the number of unpaired d-electrons. As the number increases the strength also increases. Due to the absence of unpaired electrons 'Zn' is not a hard metal.
Extraction of Iron
Iron is the most abundant metal which occurs in the earth's crust. There are two forms of iron - cast iron and wrought iron - cast iron is the least pure form of iron whereas wrought iron is the purest form of iron. There are many ores of iron. Among all the ores hematite and magnetite are the important ones. Hematite is mostly found in the northern region in India whereas magnet is found in the southern states.
Extraction of Copper
Copper occurs both in combined state and free state. It also contains many ores. The important ores of copper are copper pyrites (CuFeS2), cuprite and copper glance. The copper ores are mostly found in the north of India.
Extraction of Silver
Silver also occurs both in combined state as well as in free state. The important ores of silver are: Argentite (Ag2S), Copper silver glance, Horn silver, Ruby silver. The silver ores are found along with gold ores in some parts of India.
Extraction of Zinc
Zinc occurs only in combined state. The important ores of zinc are zinc blende (Zns), calamine etc. These two are the important ores for the extraction of zinc.
Extraction of Mercury
The only important ore of mercury is cinnabar (HgS). This ore is mostly found in foreign countries.
Alloys
Steel
Steel contains normally 0.1 to 0.5% of carbon. Silver is alloyed with copper. The ornaments made with silver copper alloy has 80% silver and 20% copper. Silver is used in silver plating. Silver salts are used in photography.
Copper Sulphate
Copper sulphate is obtained as blue crystals in the laboratories. Hence on a large scale, it is prepared in crystalline form. Copper sulphate is obtained by passing air through mixture of copper and dilute sulphuric acid. This forms CuSO4 solution. This on evaporating forms blue crystals.
Silver nitrate
In the preparation of silver nitrate dilute nitric acid is used. Silver combines with HNO3 and forms silver nitrate.
AgCl (Silver chloride)
As studied above, AgNO3 combines with chloride ions and forms AgCl precipitate.
Mercury Chloride
Hg2Cl2 is known as calomel. It is prepared by heating HgCl2 and Hg in an iron vessel.
Potassium dichromate
It is prepared from chromite ore (FeCr2O4). This preparation involves many steps.
Potassium Permanganate
It is prepared from the mineral pyrolusite (MnO2).
Photography
It is a process by which an exact image of any object can be made on a print out paper. This process is done with the help of light. Photography involves many steps. A film is prepared in dark and is fitted into camera. The image of any object falls on the film and a latent image is produced on the film. This film is to be developed to make a visible image.
f - block Elements
The f - block elements are also called as inner transition elements. As the last electron enters the f-orbital these elements are called as f - block elements. These are divided into two series. They are: Lanthanides and actinides. Lanthanides are the elements in which the last electron enters into 4f - orbital. Actinides are the elements in which the last electron enters into 5f-orbital.
Actinides
These are called second inner transition series. The elements in which the last electron enters one of the 5f-orbitals are called as actinides (or) 5f-block elements. They include the elements from actinium (Ac) to Lawrencium (Lr). All these elements are radioactive and the elements beyond uranium are all man-made elements.
Brief Comparision of Lanthanides and Actinides
Similarities
1) Both lanthanides and actinides involve in filling of f-orbitals.
2) Both exhibit common oxidation state of +3.
3) Both are electropositive and very reactive.
