What is Element | Basic concept of element | Chapter Fundamental of chemistry | скачать в хорошем качестве

What is Element | Basic concept of element | Chapter Fundamental of chemistry |

In the early ages, only nine elements (carbon, gold, silver, tin, mercury, lead, copper, iron and sulphur) were known. At that time, it was considered that elements were the substances that could not be broken down into simpler units by ordinary chemical processes. Until the end of nineteenth century, sixty-three elements had been discovered. Now 118 elements have been discovered, out of which 92 are naturally occurring elements. Modern definition of element is that it is a substance made up of same type of atoms, having same atomic number and cannot be decomposed into simple substances by ordinary chemical means. It means that each element is made up of unique type of atoms that have very specific properties. Elements occur in nature in free or combined form. All the naturally occurring elements found in the world have different percentages in the earth's crust, oceans and atmosphere. shows natural occurrence in percentage by weight of some major elements around us. It shows concentrations of these major elements found in the three main systems of our environment. #elements #chemistry