EVERYDAY SCIENCE

Detailed explanation-1: -The ionization energy of the elements within a group generally decreases from top to bottom. This is due to electron shielding. The noble gases possess very high ionization energies because of their full valence shells as indicated in the graph. Note that helium has the highest ionization energy of all the elements.

Detailed explanation-2: -The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.

Detailed explanation-3: -In general, ionization energy increases across a period and decreases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant.

Detailed explanation-4: -In general, the first ionization energy increases as we go from left to right across a row of the periodic table. The first ionization energy decreases as we go down a column of the periodic table.

Detailed explanation-5: -Ionization enthalpy decreases down the group due to increase in atomic size and the outermost electron being increasingly farther from the nucleus, there is an increased shielding of the nuclear charge by the electrons in the inner levels.