After the Big Bang, the universe consisted of about 99.9999% hydrogen (ie atoms with one proton and one electron), with the remainder being mostly helium and probably a few atoms of lithium.
In a star, the cycle of "burning" hydrogen produces heavier elements, up to iron (which has 26 protons and usually 26 electrons.) When the iron content of a star starts to impede the nuclear furnace, it is likely to explode. This explosion produces enough energy to fuse even heavier elements. All of the nickel, copper, zinc, silver, gold, etc found on Earth were synthesized when a star blew up.
On Earth, the heaviest naturally occuring element found in any quantity is uranium, with an atomic number (number of protons) of 92. Heavier elements might be created in novae, but they are unstable and tend to decay into lighter elements. We have been creating small amounts of "trans-uranium" elements for several decades, usually by slamming smaller atoms together and hoping they stick. Plutonium, with an atomic number of 94, can be made by slaming deuterium (a form of hydrogen) into uranium, producing first neptunium (with 93 protons) then plutonium.
Most trans-uranium elements are short lived. Fermium, with 100 protons, has a "half life" of about 3 minutes. A half-life is a statistical value that provides the stability of an element. For fermium, it means that, given any amount of the pure element, half will turn into a lighter element in about 3 minutes. Three minutes latter, half of the remaining fermium will decay into something else. After nine minues (three half lives), only 1/8th of the original amount is still fermium.
In the interest of scientific exploration, physicists have been synthesizing heavier and heavier elements. Often times, these elements are so unstable that they have half-lives measured in seconds. What makes it so fascinating is that exploration has, so far, confirmed predictions made by the periodic table of elements. Ununoctium (Latin for "element 118") should be a noble gas, chemically related to radon, xenon, neon and helium. According to the Wikipedia article for
ununoctium, it has a half-life of about 0.86 microseconds and decays first into ununhexium ("element 116"), then seaborgium (element 102.)
Added: Wikipedia link to the
Periodic Table. With that, you can click on any of the elements to pull up the article about that element.