Write the number of periods and groups in the Modern Periodic Table. How does the metallic character of elements vary on moving (i) from left to right in a period, and (ii) down a group?

The Modern Periodic Table has 7 periods and 18 groups.

(i) Metallic character decreases from left to right across a period. This is because, as we move from left to right across a period, the atomic number increases, and the number of electrons in the outermost shell increases. The effective nuclear charge increases due to a greater number of protons in the nucleus, pulling the valence electrons more tightly towards the nucleus. This makes it more difficult for the atom to lose electrons and therefore reduces its metallic character. Electronegativity increases and ionization energy increases across a period, supporting this trend.

(ii) Metallic character increases down a group. As we move down a group, the atomic size increases. The outermost electrons are further away from the nucleus, and the effective nuclear charge experienced by these electrons decreases. This makes it easier for the atoms to lose electrons, enhancing their metallic character. Electronegativity decreases and ionization energy decreases down a group, supporting this trend.