Where can I find the 20 human-made elements?
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At the bottom of the perodic table...\n\nThey are technetium (at. no. 43), which was the first element to be synthesized, promethium (at. no. 61), astatine (at. no. 85), francium (at. no. 87), and the transuranium elements (at. no. 93 and beyond in the periodic table). Some of these elements have since been shown to exist in minute amounts in nature, usually as short-lived members of natural radioactive decay series (see radioactivity).\n\nThe synthetic elements through at. no. 100 (fermium) are created by bombarding a heavy element, such as uranium or plutonium, with neutrons or alpha particles. The synthesis of the transfermium elements (elements with at. no. 101 or greater) is accomplished by the fusion of the nuclei of two lighter elements. Elements 101 through 106 were first produced by fusing the nuclei of slightly lighter elements, such as californium, with those of light elements, such as carbon. Elements 107 through 112 were first produced by fusing the nuclei of medium-weight elements, such as bismuth or lead, with those of other medium-weight elements, such as iron, nickel, or zinc. Element 114 was first produced by fusing the nuclei of plutonium and calcium and subsequently by fusing the nuclei of lead and krypton, as was element 116. Element 115 was produced by bombarding americium with calcium, and element 113 resulted from the radioactive decay of element 115. The claim by Lawrence Berkeley National Laboratory to have created element 118 has been retracted.)\n\nThe transfermium elements are produced in very small quantities (one atom at a time), and identification is therefore very difficult because of half-lives ranging from minutes to milliseconds and the need to identify the products by methods other than known chemical separations. This has led to controversy over reported discoveries and over the naming of the elements. It has been predicted that one isotope of element 114—containing 114 protons and 184 neutrons—would be very stable because its nucleus would have a full complement of protons and neutrons. Termed an “island of stability,” its half-life might be measured in years. However, none of the three isotopes of element 114 synthesized as yet have as many as 184 neutrons, and their half-lives are still in the millisecond range.
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http://www.schoolscience.co.uk/periodictable.html\nhttp://www.webelements.com/
817102
They're constantly adding new ones.  The new ones are synthetically created by bombarding already existing elements with neutrons.  Apparently, they're up to atomic no. 118, now:\n\nhttp://www.webelements.com/webelements/scholar/
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Theres a huge list at:\nhttp://www.zensur.freerk.com
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http://download.java.net/jdk6/docs/api/javax/lang/model/util/Elements.html
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14 of each\n\nhttp://www.webelements.com/webelements/elements/text/Ag/ionz.html
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The periodic table as of Oct. 2005 according to IUPAC shows 111. But the elements with atomic numbers 112, 114, and 116 have been reported but not have not been fully authenticated as of September 2003 (Pure Appl. Chem. 75(10), pp. 1601-1611, 2003).
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Hey there, I haven't found how to access the ones you're looking for, but I came across this one, that may have many that were there as well. It's worth a look.\n\nhttp://www.rexresearch.com/1index.htm
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There are actually 111 confirmed elements.  There are 5 more elements (though they are not recognized by the ACA), that have been produced by scientists artificially.
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http://www.chemicalelements.com/elements/br.html
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Most of the elements in the periodic table are natural, but all of the lanthanoid, actinoid, and radioactive elements are synthesized...or manmade!
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I just found some at www.scrappindaisy.com and also at www.kidscraftsonline.com.  \n\nHope that helps!
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plutonium. neptunium, mercury ,uranium
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There are various means of determining this, and without any specific data on what elements are involved in the answer you are looking for, the link below is the best reference I can find that can answer this question in a mostly generalized way.
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It depends on if you are looking at large quanities or just any ammount goes. It also depends on if you are looking at elements that are only found in compounds or not. Oxygen, hydrogen, argon, carbon, nitrogen, alluminium, silicon, iron, tugstan, lithium, potassum, titanium to name a few. almost all of the elements can be found near the earth's surface except those that are man made, usually the extremly heavy ones like plutonium.
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Omg theres like 100! lol! Check out the site below. It'll tell you everything.
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http://www.elements.nb.ca/index1.htm\nhttp://www.chem4kids.com/files/elem_intro.html\nhttp://www.chemicalelements.com/\nhttp://aleph0.clarku.edu/~djoyce/java/elements/toc.html