CBSE Class 12 Chemistry Chapter 8 - d and f Block Elements Notes - Free PDF Download
FAQs on The D and F Block Elements Class 12 Notes PDF - CBSE Chemistry Chapter 8
1. Explain the Features of d-block Elements?
The general electronic configuration of the d-block elements is given by (n −1) d1-10 ns1-2, where (n −1) stands for the inner d orbitals
In the d-block, each horizontal row consists of 10 elements as d-subshell, and it can accommodate a maximum of 10 electrons
The d-block elements with the incompletely filled d-subshell are known as transition metals
2. Give the Characteristics of Actinoids and Lanthanoids?
Lanthanoids are silvery-white soft metals which tarnish readily when they are exposed to air
The hardness of the lanthanoids increases with an increase in the atomic number
The melting point and boiling point of actinoids are moderately high, but they are considerably lower to that of transition elements
3. Explain the Characteristics of f Block Elements?
In general, these elements have a higher melting point and boiling point
These are usually heavy metals
They are the elements that tend to form coloured ions
They also display a variety of oxidisation states
They can form complex compounds
4. What are the transition elements? Write 3 characteristics of the transition elements.
Elements whose d-orbital is partially filled in the ground states or in any one of the oxidation states of the element are known as transition elements. Their characteristics are:
Showing variable states of oxidation.
Forming coloured ions.
Forming complex compounds.
5. What is lanthanoid contraction?
The overall decrease in atomic and ionic radii with an increase in atomic number is known as lanthanoid contraction. The size of the ion decreases as the lanthanide series progresses from La+3 to Lu+3. The lanthanoid contraction refers to the drop in size in the series. This occurrence occurs as a result of a 4f electron being imperfectly shielded by a separate election from the same subshell.
6. Mention the main consequences of lanthanoid contraction.
The similarity of properties because of the lanthanoid contraction, size of elements following (Hf – Hg) become very similar to the size of the previous row elements (Zr – Cd) and therefore they become difficult to make out. Because of small changes in the atomic radii, the properties of lanthanoids are also almost similar making separation very difficult.
Basicity difference is because of the lanthanoid contraction, where size reduces from La+3 to Lu+3. Therefore the covalent character improves. Thus, the basic characteristic of the hydroxides also reduces i.e. the reason La(OH)3 has the highest basicity while Lu(OH)3 has the least.
7. What is meant by ‘’disproportionation’?
Lanthanide contraction is the general reduction in atomic and ionic radii with increasing atomic number. When the lanthanide series proceeds from La+3 to Lu+3, the ion's size decreases. The lanthanoid contraction refers to the series' decrease in size. This happens when a 4f electron is poorly protected by a distinct election from the same subshell.
8. Why do transition elements show variable oxidation states?
Since there is relatively little energy difference between the (n-1) d-orbital and ns-orbital, transition elements have varying oxidation states. Due to the little difference in energy between the orbitals, both energy levels can be utilized to establish a bond. As a result, transition elements can have a range of oxidation states.
9. What is the d and f block elements class 12 notes?
D and f-block Class 12 NCERT notes provide detailed information about the elements belonging to the d-block and f-block of the periodic table. These notes cover their electronic configurations, properties, and trends in chemical behavior, as outlined in the NCERT textbook for Class 12.
10. What are the basic concepts of D and f-block elements?
The basic concepts of D and f-block elements include understanding their electronic configurations, oxidation states, magnetic properties, and chemical reactivity. Students learn about the transition metals' ability to form colored compounds, act as catalysts, and exhibit variable oxidation states, while the f-block elements often display lanthanide contraction and actinide series characteristics.