5. Discovering elements and their abundance

The discovery of elements is sometimes the subject of controversy. In some cases, a distinction must be made between the scientist who discovered an element and the one who isolated it (table 5 ).

The abundance of elements is also shown in this table. It is interesting to note that ten elements (oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, hydrogen and titanium) account for 99.1% by mass of the earth's crust, oceans and atmosphere (figure 1 a). In the human body, six elements (oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus) account for 99.2% by mass (figure 1 b). A number of minority elements are nonetheless essential...