(a) Does metallic character increase, decrease, or remain unchanged as one goes from left to right across a row of the periodic table? (b) Does metallic character increase, decrease, or remain unchanged as one goes down a column of the periodic table? (c) Are the periodic trends in (a) and (b) the same as or different from those for first ionization energy?

Metallic character refers to the degree to which an element exhibits the properties of metals, such as luster, malleability, ductility, and electrical conductivity. In general, metallic character decreases across a row (left to right) and increases down a column in the periodic table.

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. In general, ionization energy increases across a row (left to right) and decreases down a column in the periodic table.

As we move from left to right across a row in the periodic table, the number of protons in the nucleus increases, causing a greater effective nuclear charge and a stronger attraction between the nucleus and the valence electrons. This makes it more difficult for an atom to lose an electron and exhibit metallic properties. Therefore, the metallic character decreases as we move from left to right across a row.

As we move down a column in the periodic table, the number of electron shells increases, making the valence electrons further away from the nucleus and less tightly held by the effective nuclear charge. Consequently, it becomes easier for an atom to lose an electron and exhibit metallic properties. Therefore, the metallic character increases as we move down a column.

The trends in metallic character are opposite to those in ionization energy. As metallic character decreases across a row (left to right) in the periodic table, ionization energy increases. This is because it becomes more difficult to remove an electron from an atom with higher effective nuclear charge, and thus, ionization energy increases. Similarly, as metallic character increases down a column in the periodic table, ionization energy decreases due to the increased distance of the valence electrons from the nucleus, which makes it easier to remove them. In conclusion: (a) Metallic character decreases as one goes from left to right across a row of the periodic table. (b) Metallic character increases as one goes down a column of the periodic table. (c) The periodic trends in metallic character are opposite to those for the first ionization energy.