The question asks for the ionic radii of N^3–, O^2–, and F^–. These are all isoelectronic species, meaning they have the same number of electrons. All three ions have 10 electrons, the same as the neon atom (Ne).

For isoelectronic species, the ionic radius decreases as the nuclear charge (atomic number, Z) increases. This is because a greater positive charge in the nucleus pulls the electron cloud closer, making the ion smaller.

Let's list the ions with their nuclear charges:

• N^3–: Atomic number (Z) = 7
• O^2–: Atomic number (Z) = 8
• F^–: Atomic number (Z) = 9

Since they all have the same number of electrons, the ion with the smallest nuclear charge (N^3–, Z=7) will be the largest, as the electrons are less strongly attracted to the nucleus. The ion with the largest nuclear charge (F^–, Z=9) will be the smallest.

Therefore, the order of increasing nuclear charge and decreasing ionic radius is:

N^3– > O^2– > F^–

Now, comparing the given options:

Option 1: 1.71, 1.40, 1.36 (Large → Small)

Option 2: 1.36, 1.40, 1.71 (Small → Large)

Option 3: 1.71, 1.36, 1.40 (Large, Small, Medium - Incorrect order)

Option 4: 1.36, 1.71, 1.40 (Small, Large, Medium - Incorrect order)

Only Option 1 shows the radii in the correct decreasing order: largest (N^3–), medium (O^2–), smallest (F^–).

Related Topics & Formulae

Isoelectronic Series: A group of atoms and ions that contain the same number of electrons. The size in an isoelectronic series decreases with increasing atomic number (Z).

Formula for Trend: For isoelectronic species, Ionic Radius ∝ 1 / (Nuclear Charge)