Actinide

The actinide series derives its name from the first element in the series, actinium (since ˝actinide˝ means ˝like actinium˝. This series is the row below the Lanthanide series, which is located underneath the main body of the periodic table. The actinides are often referred to as Rare Earth Metals. The members of this series are actinium (Ac), thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fe), mendelevium (Md), nobelium (No) and lawrencium (Lw).

These elements are all radioactive and have high diversity in oxidation reaction. The actinides belong to the f-block elements because the series mostly corresponds to the filling of the 5f shell. They all have very large atomic and ionic radii and exhibit a large range of physical properties. The electronic configurations of the actinides are specific due to the following:

• The energy in the 6d orbital is lower in energy than in 5f orbital.
• They fill 5f orbital, 6d orbital, then 7s orbital.
• The 5f orbital is not shielded by the filled by the 6s and 6p subshells.
• There is small energy gap between the 5fn 7s2 and 5fn-1 6d 7s2 configurations.
• The 5f orbital does not shield each other from the nucleus effectively.
• The energy of the 5f orbital drop rapidly with increasing atomic number.

The best way to understand how the orbitals are filled is to follow the diagonal rule:

The actinides common properties are as follow:

• They are all radioactive due to instability.
• Majority synthetically made by particular accelerators creating nuclear reaction and short lasting.
• All are unstable and reactive due to atomic number under 83 (nuclear stability).
• All have silvery or silvery-white luster in metallic form.
• All have the ability to form stable complexes with ligands, such as chloride, sulfate, carbonate and acetate.
• Many of the actinides occur in nature as sea water or minerals.
• They have the ability to undergo nuclear reactions.
• The emission of radioactivity, toxicity, pyrophoricity and nuclear criticality are properties that make them hazardous to handle.
• Emission of radioactivity: The types of radiation the elements posses are alpha, beta, gamma, as well as neutrons are produced by spontaneous fission of boron, beryllium and fluorine react with alpha particles.
• Toxicity: Because of their radioactive and heavy metal characteristics, they are considered toxic elements.
• The interaction of the actinides when radioactive with different types of phosphors will produce pulses of light.      

Among the actinides, primordial thorium and uranium occur naturally in substantial quantities. The radioactive decay of uranium produces small amounts of actinium and protactinium, and atoms of neptunium and plutonium are occasionally produced from tansmutation reaction in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons test have released a few heavier actinides than plutonium into environment.

The most important uses of radioactive actinides are producing of nuclear weapon and as a fuel in nuclear reaction for power production. These two areas exploit the properties of actinides to release enormous energy in nuclear reactions, which under certain condition may become self-sustaining chain reaction. The most important isotope for nuclear power applications is uranium-235 which is used thermal reactor. The actinides have not stable isotopes because their nucleuses are very large (due to large number of protons and neutrons). That is why their nucleuses decay and release alpha, beta and gamma rays. Otherwise, they have a lot of unstable isotopes like uranium, thorium or plutonium. Isotopes are the atoms with same number of protons, but differing number of neutron in nucleus. In other words, they have different atomic weights. Isotopes are different forms of a single element.

                                 Nuclear reactor                    

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