What are actinides?
Actinides is a collective name given to the elements of 90-103 in the periodic table, including Thorium, Protactinium, Uranus, Neptunium, Plutonium, Americium, Curium, Berkelium, Einsteinium, Fermium, Mendelevium, Nobelium and Lawrenium. An actinium element, atomic number 89, after which the group is named, is not - strictly speaking - one of the actinides itself, but is often included with them. As with all the more heavier elements than lead, none of the actinide series has any stable isotopes, and all are therefore radioactive, generally undergoing alpha disintegration into other elements. Uranus and thorium naturally occur along with traces of actinia, protacitinia, plutonia and Neptunia. The remaining elements have never been observed in nature, but were made in extremely small quantities in the accelerator particles. It is a tee that a large part of the heat in the core of the ground that controls tectonics and volcanic plate is caused by a radioactive disintegration of these elements. Isotop plutonium-244 has a relatively long half-life and traces of the original plutonium of the country still surviveí í; However, most Plutonia in the environment come from nuclear reactors and nuclear weapons tests. Naturally occurring actinium, protactinium and neptunium have much shorter half -lives, so any amount of these elements that were present when the Earth was created would have long ago disintegrated into other elements. Actinium, protacitinium and non -tech forms through nuclear processes associated with the disintegration of uranium isotopes.
Like lanthanide elements, actinides occupy a separate block from the main periodic table, as is usually shown, because of their electron configurations. In both of these blocks, the farthest Electron Subshell was occupied before the previous Subshell, because it has a higher energy level, and it is the number of electrons in this subsell, which distinguishes elements from each other. The 4F Subshell is important for Lanthanides, and for actinides, 5f Subshell. These elements are also knowné as F-Block elements. The farthest podshell is the same for all elements in each block, with the exception of the Lawrence, which differs from the previous element, not in PodShell 5F, but has another 7p Subshell containing one electron.
Actinide chemistry is governed by the fact that valence electrons that can connect with other atoms are not limited to the furthest subsell, which provides a variable number of oxidation between these elements. For example, plutonium may have oxidation states from +3 to +7. All elements are chemically reactive and are quickly oxidized in the air and are coated with an oxide layer. Reactivitys increase with atomic weight in the group; However, the investigation of the chemical properties of some heavier members is difficult due to their intensive radioactivity and very short half -time.
isotopes with longer lifetime found different uses. Thorium has been used since the end of the 19th century in the production of gas tires. The ability of some isotopes of uranium and plutonia to undergo nuclear cleavage led toTheir use in nuclear reactors and nuclear weapons and plutonium was also used as a long -term energy source for spacecraft. America is used in smoke detectors.