Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

Identify the wrong statement in the following:

Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius

Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius

Atomic radius of the elements increases as one moves down the first group of the Periodic Table

Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the Periodic Table

Let's analyze the statements based on periodic trends and isoelectronic species:

Isoelectronic Species: These are species with the same number of electrons. Their size is governed by the nuclear charge ( $Z$ ). A higher nuclear charge exerts a stronger attraction on the electrons, shrinking the radius .

Cations: Comparing isoelectronic cations (e.g., $Na^+$ and $Mg^{2+}$ ), the one with the smaller positive charge ( $Na^+$ ) has fewer protons ( $Z=11$ ) than the one with the larger charge ( $Mg^{2+}$ , $Z=12$ ). Fewer protons mean less attraction, resulting in a larger radius. Therefore, the statement "smaller the positive charge... smaller is the ionic radius" is incorrect.
Anions: A greater negative charge means fewer protons relative to electrons, leading to reduced effective nuclear charge and increased electron-electron repulsion, which expands the radius. This statement is correct .

Group Trend: Atomic radius increases down a group (e.g., Group 1) due to the addition of electron shells shielding the outer electrons . This statement is correct.
Period Trend: Atomic radius decreases across a period (e.g., 2nd period) due to increasing effective nuclear charge pulling valence electrons closer . This statement is correct.

Practice Mode Available

Join thousands of students and practice with AI-generated mock tests.