Question Detail
Question
Valence electrons do not __________ each other effectively, so effective nuclear charge increases across a period.
Correct Answer
Option B is the correct answer.
Detailed Explanation
Electrons in the same shell (valence electrons) are poor at shielding each other from the nucleus. Therefore, as protons are added, the effective nuclear charge felt by valence electrons increases significantly.
Hint
They don't block the nuclear charge from each other well.