I don't understand, according to the periodic table at web elements;

An isotope of Element 116 (292Uuh) was identified in the reaction of 248Cm with 48Ca. It is very shortlived and decomposes to a known isotope of element 114, 288114Uuq.

How can it be that ununhexium is shortlived and decomposes, my OU books harp on about atoms not being able to decompose, atoms always stay the same but are merely attracted to different atoms.

Does anybody catch my drift.

While were on the subject of ununhexium, how do we know it exists if weve not even found it yet, let alone give it a specific place in the table? Do they want to have a guess at what aliens look like and what kind of houses they live in while they're at it?

For starters, it is good to be skeptical and it is good to inject some humor along with being skeptical, but let's not make things harder than they are. Do I detect a slight chip on the shoulder? Your question is a good one.

You are correct about atoms not being able to decompose (in some senses) and always stay the same but attract different atoms. BUT the decomposition we are talking about with Uuh is the decomposition of the nucleus; i.e., radioactivity. I know you have heard about radioactivity. Nuclei of many many elements decompose giving off alpha and or beta particles as well as gamma rays. So while most atoms do stay the same, the nuclei of many decompose to more stable arrangements. And the "while we're on it bit," your post said it had been discovered by bombarding 238Cm and 48 Ca (or is that 40 Ca?) so it must have been discovered. As to where it's placed, if it has an atomic mass of 116, then it must follow 115 and precede 117 (although they have not yet been discovered yet.) One thing that is nice about the periodic table is that we can often predict the properties of elements even before they have been discovered. In fact, that is why Mendeleev's arrangment in one of the first periodic tables back in the early days was so successful. He successfully predicted that eka-silicon (now named germanium), unknown at the time, would be discovered one day and it would have such and such properties. It was discovered about 16 years later and the properties were very close to the predictiions of Mendeleev. I hope this helps clear up any confusion about stability of atoms and where they are placed in the periodic table.

The decomposition of elements, or more specifically, the decomposition of their nuclei, is a phenomenon known as radioactivity. While atoms themselves do not decompose in the sense that their fundamental particles change, the nuclei of some elements can undergo a process of decay, resulting in the release of alpha and beta particles, as well as gamma rays. This decomposition leads to the formation of more stable nuclei.

In the case of Element 116 (ununhexium or Uuh), the isotope in question is short-lived because its nucleus is unstable and tends to break apart quickly. This instability is characteristic of many superheavy elements, which have large numbers of protons and neutrons in their nuclei, making them more prone to decay.

Regarding the existence of ununhexium and its placement in the periodic table, scientists have indeed discovered this element through experiments involving the bombardment of 248Cm (curium) with 48Ca (calcium) atoms. By analyzing the resulting products and their decay pathways, researchers can identify the existence of new elements.

Although ununhexium is short-lived and may not persist for long in nature, its discovery and identification allow scientists to assess its properties and categorize it within the periodic table according to its atomic number (in this case, 116). Even if elements have not been found naturally or are only stable for a brief time, they can still be recognized and allocated a place in the periodic table based on their atomic characteristics.

Predictive power also plays a role in placing new elements in the periodic table. Mendeleev, the creator of the original periodic table, successfully predicted the existence and properties of elements like germanium (then known as eka-silicon) before they were discovered. These predictions were based on the periodic patterns and trends observed in the already-known elements.

In summary, while it is true that atoms themselves do not decompose, the nuclei of certain elements can undergo radioactive decay. Ununhexium has been discovered through experimental studies, allowing it to be placed in the periodic table based on its atomic number. The periodic table not only organizes known elements but also provides a framework for predicting the properties of undiscovered elements.