Why and how elements are arranged in a Periodic Table?
Answer: Reason for arrangement of elements in the periodic table “OR” Why elements are arranged in the periodic table : There are more than 100 elements discovered and research is in progress to discovered more elements. Properties of each elements are difficult to study. So it is the basic reason for arrangement of elements in the periodic table.
Method of arrangement of elements in the periodic table “OR” How elements are arranged in a Periodic Table: The tabular arrangement of elements according to atomic number as based on periodic law is called periodic table. So elements are arranged in periodic table according to increasing atomic number from left to right in horizontal rows.
When elements are arranged on this method, properties of elements were found repeating after regular interval. such that elements with similar properties and similar electronic configuration are placed in the same group. It was observed that after every eighth element ninth element had similar properties to the first element. It is due to the same number of electrons in the valence shell. For example: Sodium with atomic number 11 had similar properties to Lithium with atomic number 3. It is due to the same number of 1 electron in the valence shell, and so both are placed in the same group. In a period an increase in atomic number each for each element from left to right shows a decrease in metallic character.