Mendeleev’s periodic classification of elements

The periodic table is one of the fundamental bricks that is taught as an introduction to students when they start out with understanding higher levels of chemistry and physics. Mendeleev’s periodic law states that the properties of elements; both chemical and physical, are based upon their atomic masses and occur repeatedly in periods. Mendeleev’s atomic mass periodic table has its own sets of advantages and disadvantages and these are discussed below in the notes of periodic classification of elements notes.

What is the periodic table?

The periodic table is one of the fundamental bricks that is taught as an introduction to students when they start out with understanding higher levels of chemistry and physics. In simple terms, the tabular form of storing information about elements occurring naturally or artificially is called the periodic table. 

This tabulation is done according to the atomic numbers of the elements.

The name given to the rows is periods and the columns of the table are groups. Based upon certain trends, these elements are further classified into blocks. A Russian chemist going by the name Dmitri Mendeleev first proposed the periodic table and was also widely accepted.

What is Mendeleev’s periodic law?

Along with Dmitri Mendeleev another chemist by the name of Lothar Meyer also developed the periodic table for the first time. One similarity in both their tables was that they arranged the elements in tabular form according to their mass numbers.

Mendeleev’s periodic law states that the properties of elements; both chemical and physical, are based upon their atomic masses and occur repeatedly in periods.

Mendeleev had divided the elements into eight groups each represented by a roman number.

He also left gaps, so that undiscovered elements occurring in the future could occupy these.

By Mendeleev’s time, when he actually started to formulate the periodic table only 63 elements were discovered and these he arranged and formed an atomic mass periodic table.

Advantages of Mendeleev’s table

As aforementioned, mendeleev left gaps in his atomic mass periodic table and this turned out to be a huge benefit. This allowed undiscovered elements to find their place in the atomic mass table. He gave them names like eka-boron and eka-aluminium because he believed that the new found elements would resemble properties of those already existing.

Noble gases which were discovered much later, the atomic mass periodic table still had a place where the noble gases were added and that group of elements was called group zero.

Disadvantages of Mendeleev’s table

Mendeleev placed the hydrogen element in group one where alkali metals were also placed because the hydrogen element too makes compounds just the way alkali metals do too. But hydrogen displays behaviour similar to halogens but Mendeleev did not explain this and continued to place hydrogen in group one.

Mendeleev also messed up the order of placing elements within their groups. He placed them in a differing order of their masses so that those elements could resemble their places in the groups with similar properties.

Conclusion

The periodic table is one of the fundamental bricks that is taught as an introduction to students when they start out with understanding higher levels of chemistry and physics. Mendeleev’s periodic law states that the properties of elements; both chemical and physical, are based upon their atomic masses and occur repeatedly in periods.