Final answer:
The question deals with the oxidation states of lanthanides, focusing on Ln (III) compounds while also recognizing +2 and +4 ions. It highlights the importance of various oxidation states in understanding the chemical behavior of these inner transition metals, which are crucial to many modern technologies.
Step-by-step explanation:
The question posed pertains to the oxidation states of elements within the lanthanide series, where the trivalent (III) oxidation state is most common. However, some lanthanide elements can also exhibit divalent (+2) and tetravalent (+4) ions in certain situations. In chemistry, especially when dealing with transition metals and inner transition metals like lanthanides and actinides, it's significant to remember that these metals can form various oxidation states. This is important in predicting and understanding the chemical behavior of their compounds.
Lanthanides are used in a multitude of devices due to their unique magnetic, catalytic, and luminescent properties. Despite being labeled as rare, elements like thulium are more prevalent in the earth's crust than commonly known precious metals such as silver. The term 'rare' in this context historically referred to the difficulty in economically separating these elements due to their chemical similarities. Thankfully, modern separation technologies like ion exchange resins have made it easier to isolate these elements. Understanding the varying ionic states of lanthanides helps us appreciate the formation and application of these elements in today's technology.