Among the following, the energy of 2s orbital is lowest in:
Structure of Atom · Class 11 · JEE Main Previous Year Question
Among the following, the energy of 2s orbital is lowest in:
- a✓
K
- b
H
- c
Na
- d
Li
K
🧠 The Nuclear Pull The energy of a specific orbital (like ) depends on how strongly the nucleus "grips" it. More protons () = stronger grip = lower (more negative) energy level.
🗺️ Atomic Number Check
- H:
- Li:
- Na:
- K: Since Potassium (K) has the highest atomic number, its electrons are submerged deeper into the potential well than those of the lighter elements.
⚡ The -Scaling Rule For any common subshell (like or ), the energy becomes more negative as you move down a group. The "floor" of the energy well gets deeper as you add protons.
⚠️ Common Traps Don't confuse "lowest energy" (deepest well) with "lowest principal shell" (highest well). K has the lowest energy because it has the strongest positive nucleus in this set.
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