The d and f Block elements in the groups of 3 to 11 are also called as transition elements and inner transition elements respectively. 4f and 5f orbitals of f-block elements are steadily in later of two long periods. Based on this they are differentiated in lanthanides and actinides. The d block elements which are transition elements have partially filled (n-1) d-orbitals. The position in the periodic table of an element is highly reflective of its properties and nature. Let us learn more about the position in the periodic table.
Position in the Periodic Table
Studying which elements lie in a particular group position in the periodic table, is significant to the understanding of such elements as a whole. There is a reason why we categorize different elements in the periodic table. The d and f block elements hold certain properties, which make them fall into the category. Let us study the d and f block elements’ position in the periodic table.
d Block Elements in Modern Periodic Table
The d block position in the periodic table consists of elements in the group of 3 to 12. In this group, the d orbitals are filled progressively. The elements which are present between the s and p block elements in the modern periodic table are called the transition elements. Transition elements usually have partly filled (n-1) d-orbitals.
In the transition elements, the last electron usually enters the penultimate d orbitals i.e. (n-1) d orbitals and that is why they are called d-block elements in the modern periodic table. The general valence shell configurations of every transition elements are (n-1) d1–10.ns0, 1, 2.
All the d-block elements are classified into four series which are called 3d, 4d, 5d and 6d series corresponding to the filled outer shells of 3d, 4d, 5d, and 6d orbitals. Present in the center of the periodic table, the ‘d’ block elements lie in the middle of the s block elements on the left, and the non-metals of the p block, to its right.
Transition Series of d Block Elements
The following are the transition series of the d block elements:
- First transition series or the 3d series: Those elements which have an atomic number from 21 to 30 are usually included in this series. Included in this series are ten elements which are Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. They always correspond to the filling of the 3d subshell.
- Second transition series or the 4d series: Included in this series are the elements which have an atomic number from 39 to 48 and are Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, and Cd. All of these elements have a corresponding filling of the 4d subshell.
- Third transition series or the 5d series: Included in this series are elements that have an atomic number from 72 to 80 and 57.
- Fourth transition series or the 6d series: Elements which have an atomic number from 104 to 112 and 89 form the elements in this group.
f Block Elements in Modern Periodic Table
The ‘f’ – block elements are also known by the name of inner transition elements. In these elements, the last electron usually enters the penultimate i.e. (n – 2) f of the orbital. The differentiating electron in transition elements may enter either 4f or 5f orbitals based upon which they are further differentiated into lanthanides and actinides.
In lanthanides, the differentiating electron enters the 4f orbital. These are cerium to lutetium. The name lanthanides fall on the elements because they arrive immediately after lanthanum. In the case of actinides, the differentiating electron enters the 5f orbitals. These are usually thorium to lawrencium.
These elements come immediately after actinium in the periodic table. The General electronic configuration of f – block elements is (n–2) f1–14(n–1) d0–1ns2. In the case of Lanthanides, the electronic configuration is [Xe]4f1–145d0–16s2 while in the case of Actinides it is [Rn]5f1–146d0–17s2
Solved Examples for You
Question: Discuss the electronic configuration of the f block elements and the general characteristics of these elements.
Answer: The general electronic configuration of f-block elements can be written as: (n-2) f1-14 (n-1) d0-2 ns2. The elements included in these two series are called the inner transition elements. It is so because they form transition series within the transition elements of d-block.
Among the general characteristics of the f block elements are the following:
- They are usually heavy metals
- These elements have a generally higher melting and boiling point
- They display a variety of oxidisation states
- These elements tend to form coloured ions
- They form complex compounds
As for the characteristics of Actinoids and Lanthanoids, we can say the following:
- Lanthanoids are silvery white soft metals which tarnish readily when they face exposure to air.
- The hardness of lanthanoids increases with increasing atomic number.
- The melting and boiling points of actinoids are moderately high but they are considerably lower than those of transition elements.
- Actinoids show different oxidation state such as +2, +3, +4, +5, +6 and +7. However +3 oxidation state is most common among all the actinoids.