Lesson 5: Introduction to f-Block Elements (Inner Transition Metals)
This lesson introduces the f-block elements, which are divided into two series: the lanthanoids and the actinoids.
- Electronic Configuration: The general electronic configuration is . The filling of the f-orbitals leads to the characteristic properties of these elements.
- Lanthanoids:
- Lanthanoid Contraction: This is a key phenomenon where there is a steady decrease in atomic and ionic radii from Lanthanum to Lutetium. This is due to the poor shielding effect of the 4f electrons. The contraction has significant consequences on the properties of the elements that follow the lanthanoids in the periodic table.
- Oxidation States: The most common oxidation state is +3, but some elements can show +2 and +4 oxidation states due to the stability of half-filled or completely filled f-orbitals.
- Properties: Lanthanoid ions are often colored and paramagnetic.
- Actinoids:
- Electronic Configuration and Oxidation States: Actinoids show a wider range of oxidation states compared to lanthanoids. This is because the 5f, 6d, and 7s orbitals are of comparable energy.
- Radioactivity: All actinoid elements are radioactive.
- Actinoid Contraction: Similar to the lanthanoids, there is an actinoid contraction, but it is less pronounced due to the poorer shielding effect of the 5f electrons.
- Differences between Lanthanoids and Actinoids: This section summarizes the key differences between the two series, including their oxidation states, chemical reactivity, and magnetic properties.
- Applications of d and f-Block Elements: The lesson concludes with a brief overview of the importance of these elements in various fields, such as alloys, catalysts, and nuclear energy
