Mendeleev’s periodic table is an arrangement of elements in an increasing atomic mass order in a tablet form, such that it reflects similarities and trends in the behaviour of elements.
How Mendeleev arranged elements?
Mendeleev initially arranged elements, one below the other, in the order of increasing atomic weight. Elements having similar properties are placed nearby. Elements with similar properties are found in the same horizontal row. Mendeleev’s original periodic table, published in 1869, is as follows.
Mendeleev’s periodic table can be understood better by reversing the arrangement of the elements.
- Here elements are, arranged in an increasing order atomic mass, in a horizontal line.
- This horizontal arrangement of elements is a ‘period’.
- When an element has high similarity to an earlier element, the new element is, placed just below the earlier element having similar property to start a new period.
- The period’s one below the other form a ‘column’ (group). Thus, Mendeleev’s periodic table consists of horizontal rows and vertical columns or periods and groups, respectively.
- If the element is similar but not very much, it is, placed below but slightly away to differentiate it. Each column will have two sub-columns (A and B) such that elements in the same sub-columns show more resemblance.