The first element in the Tallium Family, Tallium X is a mildly reactive, super-heavy metal, with fascinating physical properties. Its atomic number is 126.
In nature, it normally exists in a pure form, in the form of Tallium X glass. However, with the application of an electrical current, it can turn into Tallium X "plasma", a viscous liquid-like substance that blurs the lines between fluid and solid, and splits light like a prism. With enough energy, Tallium X can be caused to glow with an eerie blue colour, a property shared with many other members of the Tallium family.
Additionally, Tallium X can be found in nature in an "elevated" form, which glows naturally once exposed to a light source for a sufficient amount of time. This form of Tallium X is often referred to as "High Tallium". It can easily be confused with other Tallium family elements, which often occur in nature in the form of glowing glass.
Tallium X is highly fire resistant, because it does not react with Oxygen and charged particles easily. In combination with a heavier related element, such as Tallium 30, its fire-resistance properties become greatly amplified, and it can even resist fire while an electrical current is applied.
In its native glass form, Tallium X is very heat tolerant, even though its actual melting point is only 150°C. It has a mysterious ability to survive as a solid past conditions where its melting point has been exceeded. Vibrations or an external source of electricity can offset this effect, however, leading to the Tallium X glass melting or warping.
In its crystaline (metallic) form, Tallium X is even more resistant to heat; exhibiting a melting point of 785°C. This ceiling can be pushed even further by adding impurities such as Carbon, Silicon, Boron, Alluminium or Magnesium. The smaller atoms help to strengthen the bonds of the crystal lattice and can push the melting point further back by hundreds of degrees.
Tallium X is only mildly reactive, which comes as a bit of a surprise due to the high number of electrons it carries in numerous shells. It carries 7 valence electrons, but holds tightly to them unless they are excited by an external energy source. "High Tallium" reacts more readily, due to its electrons already being on a higher energy level.
Tallium X does not readily react with air or water, in either medium it remains pure. However, with the application of a strong electric current, Tallium X can be made to react with Oxygen or Nitrogen in the air, producing two of its most common compounds: Tallixic Oxide and Tallixic Nitride. Both compounds are formed by Tallium X giving up its valence electrons.
In nature, Tallium X can also be found occasionally in compounds with other super-heavy elements. Nastium-family elements sometimes bond with Tallium X, forming Tallixic Nastide -type compounds. These are similar to Tallixic Oxide, with the exception that they are more easily dissociated into their constituents.
Tallium X is not widely used by any known civilzation. Heavier Tallium-family elements have far more exotic properties, and are as such more attractive to engineers and scientists.
The Ta'Elans have used Tallium X in a limited capacity to make vehicle parts, electronics, batteries and fire-resistance glass. It is also used as a conditional colouring agent, due to its ability to glow when an electrical current is applied.
In science, Tallium X is often used for storing Nastium Oxide gases, because of its resistance to reacting with them, and its high temparature tolerance.