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Although lanthanoids and actinoids are f-block transition metals, their characteristics are vastly different from those of d-block transition metals. These elements are listed separately in the periodic table, indicating that their electronic structures have a different periodicity than the mainstream. Even though lanthanoids are classified as rare-earth elements, their abundance in the crust is by no means uncommon, and chemistry based on their unique features is expected to proliferate soon. Nuclear chemistry and nuclear energy are both closely related to actinoids. Because the number of superheavy elements “synthesised” in accelerators is so tiny, they are essential in applied chemistry.
Lanthanoids
Lanthanoids are chemical elements found in the periodic table’s lanthanide series of the f block. Except for Promethium, lanthanoids are non-radioactive. Lanthanoids are formed of comparatively big atoms due to their atomic numbers ranging from 57 to 71. Lanthanoids have valence electrons in the 4f orbital. Lanthanides is another name for them.
Actinoids
The actinide series of the f-block of the periodic table contains actinoids, which are chemical elements. Because of their unstable nature, all actinoids are radioactive. There are no stable isotopes in them. These elements are made up of a lot of big atoms. The valence electrons in actinides are in the 5f orbital. The actinide series includes chemical elements with atomic numbers ranging from 89 to 103.
Elemental properties
As the structure of the 4f orbitals, the chemistry of lanthanides differs from that of main group elements and transition metals.
- The 4d and 5p electrons “bury” these orbitals inside the atom, shielding them from the outside world. As a result, the chemistry of the elements is primarily dictated by their size, which steadily diminishes as the atomic number increases. The lanthanide contraction is the name for this phenomenon.
- The oxidation state of all lanthanide elements is +3.
- Metals such as actinides are common. They are all delicate, silvery in hue (though they tarnish in the air) and have a great density and flexibility.
- Knives can be used to cut some of them. Because Thorium’s hardness is close to that of mild steel, it can be rolled into sheets and twisted into wire when heated.
- Thorium has roughly half the density of uranium and plutonium, but it is much more complicated.
Significant differences between Lanthanoids and Actinoids
Lanthanoids | Actinoids |
Lanthanoids are metallic compounds with a dazzling, silvery look. They are soft, and you can cut them with a knife. | These are highly reactive elements. They easily ignite when exposed to air. Actinoids, although being metals, are incredibly soft. They can even be cut with a knife in some cases. |
Lanthanide elements such as lanthanum, cerium, praseodymium, neodymium, and europium are highly reactive compared to other members of the series. When these metals encounter air, they generate oxide coatings. As a result of this, they become tarnished. | Actinoids are all paramagnetic (an external magnetic field). Uranium and Thorium are the most prevalent and plentiful Actinoids on the planet. They are radioactively inactive, but they release much energy as they decay. |
In acids, lanthanoids disintegrate fast. They can react with oxygen and halides, but only slowly. Lanthanoids’ most prominent oxidation state is +3. Lanthanoids also have oxidation states of +2 and +4. They cannot, however, have a +6-oxidation state. As a result, they are unable to synthesise complex compounds. | The oxidation state +3 is the most common among Actinoids. Actinoids also have oxidation states, such as +4, +5, and +6. |
Locations, such as oxides and hydroxides, are not formed by lanthanoids. Lanthanoids produce more minor essential compounds. Lanthanoids produce almost all colourless ions. Electropositive elements are lanthanoids. As a result, they prefer to create molecules that contain electronegative components. On the other hand, chemical and physical properties change very little over the series. | Actinoids form basic oxides and hydroxides. They can form complexes with ligands like chlorides, sulphates, and other salts. The majority of Actinoid complexes are colourful. On the other hand, Actinoids are dangerous chemicals due to their radioactivity and heavy metal characteristics. |
Conclusion
The periodic table’s f block elements are lanthanoids and actinoids. They are metals, but they are very soft metals. They differ in terms of chemical attributes. The primary distinction between actinides and lanthanides is that actinides may quickly form complexes, whereas lanthanides cannot.
