48 weeks ago
Elements 58-71 contain lanthanoids, and elements 90-103 include actinoids. Lanthanoids, due to poor 4f-orbital shielding, cause the atomic radii of elements after them to be much lower than expected. This is termed contractions in lanthanide. Actinoids are all radioactive and most are not found naturally on earth.
127 weeks ago
Lanthanoids include 14 elements, with atomic numbers 58-71:
The actinoid series also includes 14 elements, with the atomic numbers 90-103:
127 weeks ago
?The lanthanides include the metals cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). ?Actinide series Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium
127 weeks ago
The lanthanide and actinide series make up the inner transition metals. The lanthanide series includes elements 58 to 71, which fill their 4f sublevel progressively. The actinides are elements 89 to 103 and fill their 5f sublevel progressively. ?The actinides group includes mostly man-made elements with only a few exceptions such as uranium and thorium. The actinides are most known for the elements uranium and plutonium which are used in nuclear reactors and nuclear bombs. The lanthanides and actinides are located mostly in the "f-block" of the periodic table. ?The two rows that are generally placed underneath the main Periodic Table are called the lanthanide series and the actinide series. These two rows are produced when electrons are being added to f orbitals. Therefore, this block of elements are referred to as the "f block" ??DIFFERENCE:- Lanthanoids are involved in the filling of 4f- orbitals whereas actinoids are involved in the filling of 5f-orbitals. The binding energy of 4f electrons is comparatively less than that of 5f-electrons. ... Lanthanides are non-radioactive in nature except promethium whereas all actinide series elements are radioactive.