Transition Elements - Definition, Properties, FAQs
Transition elements (also known as transition metals) are elements that have partially filled d-orbitals. IUPAC defines transition elements as an element having a d-subshell that is partially filled with electrons, or an element that can form stable cations with an incompletely filled d orbital. In general, any element that corresponds to the d-block of the modern periodic table (which consists of groups 3-12) is considered to be a transition element. Even the f-block elements comprising the lanthanides and the actinides can be considered as transition elements.
This Story also Contains
- Transition Elements-
- Some Solved Examples
- Conclusion
Several transition metals have catalytic properties that are very useful in the industrial production of some chemicals. For example, iron is used as a catalyst in the Haber process, vanadium pentoxide is used as a catalyst in the industrial production of sulphuric acid. The transition metals exhibit typical metallic properties such as malleability, ductility, high tensile strength, and metallic luster. They are generally good conductors of heat and electricity and tend to crystallize in BCC (body-centered cube), CCP (cubic close-packed), or HCP (hexagonal close-packed) structures. However, trends can be observed in the metallic properties of the transition elements. For example, elements such as chromium and molybdenum are some of the hardest transition metals because they contain many unpaired electrons
Transition Elements-
In the extended form of the periodic table, the elements have been grouped into four blocks namely s, p, d, and f-blocks. The elements belonging to groups 3 to 12 are called d-block or transition elements. In these elements, the last electron enters (n-1) d-subshell. The configuration of these elements is (n−1)d1−10ns1−2. These are present between s-block and p-block elements. The properties of these elements are intermediate between the properties of s-block and p-block elements, i.e., d-block elements represent change or transition in properties from most electropositive s-block elements to least electropositive p-block elements. Therefore, these elements are called transition elements.
Earlier, the transition elements were regarded as those elements that possessed partially filled penultimate d-subshells in their ground state or in one of their commonly occurring oxidation states. This definition included coinage metals(Cu, Ag, and Au) in the transition elements as their ions have partially filled (n-1)d-subshells although their atoms have filled(n-1) d-subshells in the ground state.
However, the above definition does not cover the elements of group 12, i.e. Zn, Cd, and Hg as these elements do not have partially filled (n-1) d-subshells either in the ground state or in ions.
Related Topics Link,
Also read -
- NCERT Solutions for Class 11 Chemistry
- NCERT Solutions for Class 12 Chemistry
- NCERT Solutions for All Subjects
However, zinc metals showing similarities in some of the chemical properties with transition metals are also included in this block. These are considered as end members of the transition series in order to maintain a rational classification of elements.
Certain d-block elements are particularly important in living organisms. Iron, the transition element, is present in the largest quantity in the human body. The best-known biological iron-containing compound is the protein hemoglobin, the red component of blood that is responsible for the transport of oxygen. Cobalt is the crucial element in vitamin B12, a compound that acts as a catalyst in the metabolism of carbohydrates, fats and proteins. Molybdenum and iron together with sulphur form the reactive portion of nitrogenase, a biological catalyst used by nitrogen-fixing organisms to convert atmospheric nitrogen into ammonia. Copper and zinc are important in other biological catalysts. Iron, zinc, copper, cobalt, nickel, manganese, and molybdenum are known to be an essential component of enzymes. Vanadium and chromium are also essential for life. Some harmful elements are also present in this block. For example, mercury is toxic and is a threat to the environment.
Recommended topic video on (Transition Elements )
Some Solved Examples
Q.1Transition metals -
1) exhibit diamagnetism
2) undergo inert pair effect
3) do not form alloys
4) show variable oxidation states
Solution:
As we learned,
Transition metals show variable oxidation states, exhibit paramagnetism, and form alloys. The inert pair effect is seen in the heavier elements of the p block and the transition elements do not show this effect.
Hence, the answer is the option (4).
Q.2 Which of the following is not the characteristic of transition metals?
1) They are all metals
2) They show variable oxidation states which always differ by two units
3) They are paramagnetic
4) They easily form complexes
Solution:
As we learned,
Transition elements are all metals and generally show variable oxidation states. Unlike p Block elements which show a difference in oxidation states by two, these elements show a difference in oxidation state of only one unit. This is because of the incomplete filling up of electrons in the d orbitals. Due to their small size and high charge density, they can form complexes
Hence, the answer is the option (2).
Also read :
Conclusion
Transition elements, also known as transition metals, are found in the d-block of the periodic table. They are characterized by their ability to form variable oxidation states and complex ions, and they often exhibit magnetic properties. These elements, such as iron, copper, and nickel, play crucial roles in various industries, and biological, and technological processes due to their unique chemical and physical properties.
Also check-
- NCERT Exemplar Class 11th Chemistry Solutions
- NCERT Exemplar Class 12th Chemistry Solutions
- NCERT Exemplar Solutions for All Subjects
NCERT Chemistry Notes:
Frequently Asked Questions (FAQs)
It is the first transition series which comes under the d block elements from group 3 to 12 of the periodic table.
Elements of the periodic table are classified in four categories 1.Main group element 2.transition metals 3.lantanides 4. Actinides, in the other words we can say that the periodic table has 4 blocks namely as s, p, d, and f out of these the d block elements are basically known as the transition metals, transition elements are named transition because their properties lie between s and p block elements of the periodic table.
When we go across the metal series from scandium there will be small change in the 1st ionization energy and the 2nd ionization energy, it happens because electrons build up occurs immediately in d-sub-shells due to which the 4s electrons are shields in the nucleus and which minimize the effective nuclear charge from one element to other . There is a rapid increase in 3rd and 4rth ionization energy,because of unpaired electrons of 5d subshell, in singly occupied orbitals.and due to this the inter electron repulsion occurs When the 6th and the further electrons enter in the shell due to which it has to share its orbital which is already occupied, and there is a less requirement of energy to remove electron.
The electronic general electronic configuration of transition elements for the first row of lower energy for transition metals is shown below.
Group of the transition metal. | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Atomic no. Symbol | 21 Sc | 22 Ti | 23 V | 24 Cr | 25 Mn | 26 Fe | 27 Co | 28 Ni | 29 Cu | 30 Zn |
general electronic configuration of transition elements | 3d1s2 | 3d2s2 | 3d3s2 | 3d5s1 | 3d5s2 | 3d6s2 | 3d7s2 | 3d8s2 | 3d104s | 3d1042 |
The chemical properties of transition metals are as follows
like sodium metal transition metals are less reactive.
Transition metals forms ions with color and also of different charges’
few of them like silver and gold are unreactive
They can also be used as a catalyst in various types of chemical reactions