Question

which of the following decreases with increasing atomic number in group 2a?
shielding effect
ionic size
ionization energy
number of electrons

Explanation:

• Shielding effect: As atomic number increases in Group 2A, the number of electron shells increases, so shielding effect increases.
• Ionic size: With increasing atomic number (more electron shells), ionic size increases.
• Ionization energy: As atomic number increases in Group 2A, atomic radius increases (more electron shells), and the outermost electrons are less tightly held by the nucleus. Ionization energy (energy required to remove an electron) decreases.
• Number of electrons: For Group 2A elements, as atomic number (which is equal to the number of protons and for neutral atoms, number of electrons) increases, the number of electrons increases.

Answer:

Ionization energy.