 The properties of elements of a sub-group                 table are better predicted by their atomic
  resemble each other more markedly than                    numbers than their atomic weights.
  the properties of those between the                      Law of Modern Periodic Table states that
  elements of the two sub-groups.                           properties of elements are the periodic
                                                            function of their atomic numbers. In the
Modern Periodic Table                                       modern periodic table, elements are
                                                            arranged in order of their increasing
                                                            atomic numbers.
                                                           The vertical columns are known as
                                                            Groups and horizontal columns are
                                                            known as Periods; in the Modern
                                                            Periodic Table.
 In 1913 Sir Henry Moseley discovered                     There are 18 groups and 7 periods in the
  that elements positions in the periodic                   modern periodic table.
                                 Long Form of Periodic Table
 This periodic table is based on the electronic configuration of elements.
 There are 118 elements have been identified.
 A block of the periodic table of elements is a set of adjacent groups.
 The respective highest-energy electrons in each element in a block belong to the same atomic
  orbital type. Each block is named after its characteristic orbital; thus, the blocks are: s-block, p-
  block, d-block and f-block