Chemistry

Periodic table


From the nineteenth century, scientists began to realize that chemical elements could be grouped into columns, formed by the gathering of elements with similar properties.

The number of chemical elements known to man has increased over the centuries, especially in the nineteenth.

Look at the table:

By the end of the century:

No. of chemical elements

XVI

14

XVII

33

XIX

83

XX

112

Some elements were known before 1650, such as Ag, C, As, Au, Hg, Pb, Sn, Sb, Cu, S.

After so many chemists try to classify the chemical elements, Dimitri Ivanovitch Mendeleyev was what stood out the most. His work in classifying elements is still used today. He created a periodic table of elements, which served as the basis for organizing what we have today.

Mendeleyev noted that there is a periodicity of properties when chemical elements are placed in ascending order of their atomic masses.

Law of Periodicity - Many physical and chemical properties of elements vary periodically following their atomic numbers.