Copy and complete the following sentences choosing the correct word or words from those given in the brackets, at the end of each sentence:
(1) The properties of the elements are a periodic function of their _________ (atomic number, mass number, relative atomic mass).
(2) Moving across a ________ of the periodic table, the elements show increasing _______ character (group, period, metallic, non-metallic).
(3) The element at the bottom of a group would be expected to show ________ metallic character than the element at the top (less, more).
(4) The similarities in the properties of elements belonging to a group is because they have the same _________ (electronic configurations, number of outer electrons, atomic number).