Question detail
What is the significance of the first ionisation energy trend across Period 3?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Atomic structure
Question
- A. It decreases due to increased shielding.
- B. It increases due to increased nuclear charge.
- C. It remains constant across the period.
- D. It decreases due to increased atomic size.
Answer
It increases due to increased nuclear charge.
Explanation
The evidence shows that as you move across Period 3, the nuclear charge increases while the shielding effect remains relatively constant. This results in a stronger attraction between the nucleus and the outer electrons. The implication is that more energy is needed to remove an electron, leading to higher first ionisation energies. Therefore, the conclusion is that the trend of increasing first ionisation energy across Period 3 is due to the increasing nuclear charge.
Common mistake
Misunderstanding Ionisation Energy Trends
Students often confuse the trends in first and successive ionisation energies, failing to recognize that successive ionisation energies increase due to the removal of electrons from an increasingly positive ion.
To fix this, students should focus on understanding that as electrons are removed, the remaining electrons experience a greater effective nuclear charge, leading to higher ionisation energies. Reviewing the concepts of electron shielding and effective nuclear charge can also help clarify these trends.
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