Lavoisier's table of elements
t the end of the 18th century, Lavoisier tabulated a list of the 33 elements and simple compounds known at that time.
At the end of the 18th century, Lavoisier tabulated a list of the 33 elements and simple compounds known at that time. By 1870, 65 elements were discovered and tabulated by D. Mendeleev and others. Today there are 116 elements to understand the properties of matter. These elements combine to form millions of compounds, some of the elements have similar properties, so there is need of organization of these elements to understand their behavior. Before going to understand the extended form of periodic table here is a discussion of early organization of elements.
The elements shown in the table were the agreed upon elements at the time of Lavoisier. The names in the right purple column were listed as elements but Lavoisier suspected that they weren't elements; he just couldn't get them to decompose. Later, lime was shown to be calcium combined with oxygen. Magnesia consisted of magnesium, sulfur and oxygen. Silex and Argill were also found not to be elements but made up of true elements.
Dalton suggested that substances around us were made up from a grouping of specific number of atoms of different elements. This idea would tremendously simplify the complexity of all the materials around us. For example, a water molecule is made from two atoms of hydrogen and one atom of oxygen. If there are 2 oxygen atoms and 2 hydrogen atoms in a molecule then it is not water but something else. Salt is made from one sodium atom and one chlorine atom. Ammonia is made from 3 hydrogen atoms and one nitrogen atom.