How many elements are there?

    There are about a 118 known chemical elements. A few of these elements have been produced in such atom-smashing machines as the cyclotron. These man- made elements are technetium (43); promethium (61); astatine (85); francium (87); neptunium (93); plutonium (94); californium (98); Einsteinium (99) etc. It seems unlikely that these manmade elements exist in a natural state. 

Scientists have been able to measure the approximate atomic weights of the different atoms. These weights do not tell   atom. instead, it has been found practical to use a system of relative weights; and in this system oxygen has  been  given  the arbitrary weight of 16. This weight was decided on because it was found that, when oxygen was given an atomic weight of 16. the weights of the other atoms compared to that of oxygen were generally close to whole numbers.ln this list the atomic weights have been rounded off to the   nearest   whole  i numbers.   tolumn three gives us the atomic numbers, which are useful because they tell us something about the complexity of the atoms. The structure of some atoms is exceedingly complex. Other atoms are comparatively simple. Atoms are listed in the order of their 'encresing Complexity by what is known as their atomic numbers. If you compare the atomic numbers and the atomic weights of the different atoms, you will see that, in most cases, the more complicated an atom the heavier it is.I the actual, absolute weight of each