Fill in the blanks in the following statements: (a) The horizontal rows in a periodic table are called . (b) In going across a period (right to left) in periodic table, the atomic size of the atom . (c) On moving from right to left in the second period, the number of valence electrons . (d) On going down in a group in the periodic table, the metallic character of elements . The tendency to gain an electron on moving down in a group of the periodic table.