Question

Answer each of the following questions:
(a) Of the elements ${{S}},{{Se}},{{Cl}}$, which has the largest atomic radius?
(b) Which has the largest radius, ${{Br,B}}{{{r}}^ - }$?
(c) Which would have the largest difference between the first and second ionization energy?
${{Si}},{{Na}},{{P}},{{Mg}}$
(d) Which has the largest ionization energy?
${{N}},{{P}},{{As}}$
(e) Which of the following has the largest radius?
${{{O}}^{2 - }},{{{N}}^{3 - }},{{{F}}^ - }$
A. (a) ${{Se}}$ (b) ${{B}}{{{r}}^ - }$ (c) ${{Na}}$ (d) ${{N}}$ (e) ${{{N}}^{3 - }}$
B. (a) ${{Cl}}$ (b) ${{B}}{{{r}}^ - }$(c) ${{Na}}$ (d) ${{N}}$ (e) ${{{N}}^{3 - }}$
C. (a) ${{S}}$ (b) ${{Br}}$ (c) ${{Mg}}$ (d) ${{N}}$ (e) ${{{N}}^{3 - }}$
D. None of these.

Answer 1

Hint: Periodic table has been developed on the basis of their atomic number. This problem can be solved if we know the periodic trends in the periodic table properly. As we know that the periodic table has seven periods and eighteen groups.

Complete step by step answer:
We’ll just move on to each question given.
(a) In a periodic table, atomic radius decreases when we move from left to right. Also, it increases when we move down the group. In a group, there is an increase in the number of shells. ${{S}},{{Se}}$ lies in the same period. So Selenium will have a larger size than others.
(b) When an atom accepts an electron, anion is formed. Thus its atomic size or atomic radius is increased. Since the effective nuclear charge is less, the nucleus pulls the electrons very less. So bromide ions will have more atomic size or atomic radius than bromine atoms, i.e. its parent atom.
(c) Ionization energy is the energy released when an electron is lost. First ionization energy is the energy released when the first electron is lost from the valence shell of the atom. Second ionization energy is the energy released when the second electron is lost from the valence shell of the atom. When an electron is lost from a sodium atom, it attains a stable electronic configuration. Thus second ionization energy will be very much higher than the first. Other elements will not have much difference in the ionization energy.
(d) In a periodic table, similar to atomic size, ionization energy increases when we move from left to right. Also, nitrogen has a half-filled orbital and it is very small in size. Thus it needs high energy. So nitrogen will have larger ionization energy than others.
(e) When electrons are gained, the effective nuclear charge is decreased. Among the given elements, nitrogen has accepted three electrons. Thus it has larger size than other anions.

So, the correct answer is Option A.

Note: These trends in periodic properties help in chemical reactions. It also helps in the physical properties of the elements. Several properties can be explained using these trends. Some of them are melting point, boiling point, metallic character etc.