Chemistry

Chemistry

Problem

The set representing the correct order for first ionisation potential (IIT 2001) a. K>Na>Li\text{K} > \text{Na} > \text{Li} b. Be>Mg>Ca\text{Be} > \text{Mg} > \text{Ca} c. B>C>N\text{B} > \text{C} > \text{N} d. Ge>Si>C\text{Ge} > \text{Si} > \text{C}
Intuitive explanation

First ionization potential measures how tightly an atom holds its outermost electron—it's about nuclear pull versus electron shielding. The key insight is that you need to balance two competing trends: moving across a period (stronger nuclear charge pulls harder) and moving down a group (more electron shells shield the outer electron). Watch out for exceptions where a half-filled or filled subshell is extra stable, making it harder to remove an electron than the trend alone would suggest.

Intuitive explanation

First ionization potential measures how tightly an atom holds its outermost electron—it's about nuclear pull versus electron shielding. The key insight is that you need to balance two competing trends: moving across a period (stronger nuclear charge pulls harder) and moving down a group (more electron shells shield the outer electron). Watch out for exceptions where a half-filled or filled subshell is extra stable, making it harder to remove an electron than the trend alone would suggest.

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