Re: Why are elements 104-109 on ref. table if wedon't know anything about them?

Why are elements 104-109 on ref. table if we don't know anything about them?

I don't understand why they are on there if we don't even know what they are and we don't even use them for anything. What are they anyway? Do they have specific names,like Ag is silver? Who "found" these elements anyway and how did they discover them? Did they just stumble over them when trying to figure out something else or were they actually focused on looking for that specific thing?

You are taking an instrumental view of science, insisting that what we do must have a "practical" application. That's no more true of science than it is of any other fine art (like painting or literature). There is "applied science," just as there are people who paint portraits and draw engineering diagrams, and people who write user manuals and textbooks, but that's not what science is about. For more, please read another of my answers.

Elements 104-109, and 110-112, and 87, and 85, and 96-103 (all of which are so unstable that they are essentially "useless") are on the periodic table because the periodic table is, first, a listing of all known elements. All of the elements of atomic number 93 and above are artificially made (not to mention element 43, which is used in medical research as a tracer, and element 85), because uranium is the heaviest element found in quantity in the Earth's crust (the other radioactive element found in quantity is thorium, 90). All higher elements (including plutonium, used as a nuclear fuel and as a thermoelectric power source for deep space probes, and americium, used in smoke detectors) are too unstable to have survived since the formation of the Earth. And elements 84, 86-89 and 91 are only found in nature because they are products of the slow decay of thorium or uranium. Most of these are too unstable to have technological uses; element 87 has never been isolated in visible quantities.

All these elements, as well as elements 110, 111, 112 and 114, were synthesized by nuclear physicists by the technique of heavy-ion bombardment. In this techique, two fairly heavy nucleii (like calcium and radium) are smashed together to form a new nucleus. None of those so far discovered are very stable, but there is a method to the madness.

The generally-accepted model of how protons and neutrons "stack" themselves in atomic nucleii is called the shell model. According to this model, a nucleus with 114 protons or 184 neutrons ought to be especially stable; the experiments in which new elements are made are, then, designed to test our understanding of the structure of the atomic nucleus.

For more information on the elements and their most common uses, consult WebElements.