Complete the following sentences choosing the correct word or words from those given in brackets at the end of each sentence:
(a) The properties of the elements are a periodic function of their atomic number (atomic number, mass number, reative atomic mass).
(b) Moving across a periods of the periodic table the elements show increasing non-metallic character (group, **, metallic, non-metallic).
(c) The elements at the bottom of a group would be expected to show more metallic character than the element at the top. (less, more).
(d) The similarities in the properties of a group of elements are because they have the same number of outer electrons (electronic configuration, number of outer electrons, atomic numbers).
