chapter 7.  ELEMENTS OF GROUPS 16, 17 AND 18 class 12 chemistry textbook solution

Answer:-

The elements in Group 16 of the periodic table, also known as the oxygen group or chalcogens, include oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). These elements exhibit certain trends in atomic properties:

i. Atomic Radii:

• Atomic radii generally increase down Group 16.
• This trend occurs because as you move down the group, each element has an additional energy level (shell) of electrons. These additional energy levels are further from the nucleus, resulting in an increase in the average distance between the electrons and the nucleus, leading to larger atomic radii.
• The outermost electrons in each element are located in the same principal energy level (n), but as you move down the group, the value of n increases, leading to larger atomic orbitals and, consequently, larger atomic radii.

ii. Ionization Enthalpy:

• Ionization enthalpy, or the energy required to remove an electron from an atom, generally decreases down Group 16.
• This trend is primarily due to the increase in atomic size as you move down the group. As the atomic radii increase, the outermost electrons are farther from the nucleus and experience weaker attraction to the positively charged nucleus. As a result, it becomes easier to remove an electron, and the ionization enthalpy decreases.
• Additionally, the electron being removed is in the same principal energy level (n), but the shielding effect of inner electrons increases, further reducing the effective nuclear charge experienced by the outermost electrons.

iii. Electronegativity:

• Electronegativity, which measures an element’s tendency to attract electrons in a chemical bond, generally decreases down Group 16.
• The decrease in electronegativity down the group is due to the same factors that influence ionization enthalpy and atomic radii. As you move down the group, the atoms become larger, and the outermost electrons are farther from the nucleus, reducing their ability to attract electrons in a chemical bond.
• Oxygen (O) is the most electronegative element in Group 16, and electronegativity generally decreases from oxygen to sulfur (S), selenium (Se), tellurium (Te), and polonium (Po).

In summary, the trends in atomic radii, ionization enthalpy, and electronegativity in Group 16 elements are all related to changes in atomic size and the effective nuclear charge experienced by the outermost electrons as you move down the group. These trends are consistent with the periodic trends observed in the periodic table.