Properties of Actinides

Actinides belong to the f block elements except for one, Lawrencium, which belongs to the d block. They comprise fifteen features ranging from Actinium (atomic no. 89) to Lawrencium (Atomic no. 103). Actinides are radioactive. They got their name from the first element in the series, known as ‘Actinium’. The symbol An denotes actinide. 

Actinides are elements that have properties similar to that of Actinium. Actinides are metallic. Hence, some of their properties are similar to metallic parts. 

Properties of actinides 

Properties of actinides are similar to lanthanides. The valence shell electrons enter into the 5f orbital of the pre penultimate shell. 5f orbitals play an excellent role in bonding than 4f orbitals because 4f orbitals are closely bonded to the nucleus. The electronic configuration of actinide is [Rn] 5f1-14 6d0-1 7s2.

Physical properties 

● The atomic or ionic radii decrease gradually when we go from left to right in the periodic table. This happens because of actinide contraction. Actinide contraction is the same as lanthanide contraction. 

● Actinide contraction is the contraction in ionic or atomic radii when we go higher in the series because of poor shielding of 5f electrons, which results in an increased nuclear attraction between the nucleus and the outermost electron. 

● They are metallic in nature. They are lustrous, which means they produce a shiny silvery effect. 

● They are soft metals and can be cut with a knife. 

● They are metals, so they are good conductors of heat and electricity; they also show ductility and malleability 

● Most actinides are naturally occurring and found in abundant amounts in nature except plutonium, as it is synthetically produced.

● Actinides have a higher density than other elements in nature and have a higher number of allotropes. For example, plutonium has six allotropes. 

● Actinides are paramagnetic metals that are not strongly attracted to magnets.

Chemical properties 

● Actinides are chemically similar due to similar electronic configuration and similar ionic and atomic radii. 

● All actinides are radioactive when they are exposed to radioactive decay (radioactive decay is a process of releasing lots of energy upon radiation). 

● Actinides produce coloured ions. When light of a specific frequency is passed through it, it absorbs a particular frequency of light and has complementary colour, which results in the formation of coloured ions. 

● Actinides show various oxidation states, but the most stable oxidation state is +3. The trends in the oxidation state of actinides are such that it first increases and then decreases. It has oxidation states like +3, +4, +5, +6, +7 and then falls. The maximum oxidation state of actinides is +7. 

● They can form several coordination complexes. They are better at forming complexes than lanthanides because of their high nuclear energy and smaller size, making them able to create several complexes. 

●  The ionisation energy (energy to remove an electron from the outermost shell) of actinides is lower than lanthanides, making them more reactive than lanthanides.

 ● Actinides react rapidly with hot water and dilute water and release an enormous amount of energy in the form of hydrogen gas. 

● They are toxic because of their radioactive nature. They do not have any stable isotopes. 

● Their solubility power in different forms like fluorides or hydroxides is lower. They also form halides. Halides can have radioactive nature, but they are instrumental in the research and study of the trends of actinides. 

● Actinides are pyrophoric, which means they will be quickly burned in the air, resulting in quick tarnishing of actinides when exposed to air. 

Uses of actinides 

● Actinides are used in making nuclear weapons and nuclear reactors. 

● They are also used as a good source of gamma radiation and an indicator too.

 ● Some of them, like plutonium, are used in making nuclear bombs and also in the creation of electronic power.

● They are used in labs by scientists for research and study. 

● They are also used as smoke detectors. Smoke particles disturb the low and steady electrical current produced by the radioactive element and switch on the alarms. 

Conclusion 

Actinides are f block elements found on the lower side of the periodic table. They are radioactive and also known as inner transition elements. Most of their properties are similar to lanthanides. They also show actinide contraction and form colourful complexes. They are good conductors of heat and electricity and are used to make nuclear bombs as well as in nuclear power plants.