Chemistry · Structure Of Atom · NEET
| Meaning | Fixed circular path of the electron | 3D region where the electron is most likely found |
| Model | Bohr model (old) | Quantum mechanical model (modern) |
| Shape / dimension | Flat circle, 2D | Definite 3D shape (s spherical, p dumbbell) |
| Uncertainty principle | Violates it (needs exact path) | Agrees with it (only probability) |
| Max electrons | 2n² electrons in nth orbit | Only 2 electrons per orbital |
| Basis | Exact position known | Probability = ψ² (position not exact) |
No. They sound alike but mean very different things. An orbit is a fixed circular path where the electron moves, an idea from the old Bohr model. An orbital is a region of space where the electron is most likely to be found (about 90 to 95 percent chance), an idea from the modern quantum mechanical model. NEET often tries to confuse you by swapping these two words, so read the question carefully.
Because of Heisenberg's Uncertainty Principle. We cannot know the exact position and exact speed of an electron at the same time. A fixed orbit needs a known path (exact position at every moment), which is impossible for such a tiny fast particle. So the sharp "road" idea was replaced by the fuzzy "cloud" idea, the orbital.
On its own, ψ has no physical meaning. It is just a mathematical function that depends on the position (coordinates) of the electron. The useful thing is ψ² (psi squared). ψ² gives the probability of finding the electron at a point in space. This is exactly what NEET 2023 tested: ψ depends on coordinates (true), but probability is proportional to ψ², not to ψ.
Because ψ can be positive or negative (it is a wave, and waves have positive and negative parts). A probability can never be negative. Squaring ψ always gives a positive number, so ψ² is used to describe the chance of finding the electron. Remember: ψ can be negative, ψ² cannot.
Only 2 electrons, and they must have opposite spins. This is fixed by the Pauli Exclusion Principle. So a single 2p orbital holds 2, not 6. The 6 electrons belong to the whole 2p subshell, which has 3 orbitals (px, py, pz). NEET 2016 asked this exact trap: n=3, l=1 is one 3p orbital, so the answer is 2 electrons.
Yes. An orbit is always a flat circle in one plane. An orbital has a 3D shape that depends on the subshell: s orbitals are spherical, p orbitals are dumbbell-shaped, d orbitals are more complex. The shape tells you the region where the electron cloud is dense.
Two statements are given. Statement I: The value of the wave function ψ depends upon the coordinates of the electron in the atom. Statement II: The probability of finding an electron at a point within an atom is proportional to the orbital wave function ψ. Choose the correct answer.
How many electrons can fit in the orbital for which n = 3 and l = 1?
Two electrons occupying the same orbital are distinguished by:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Orbit is a fixed circular path (Bohr model); orbital is a 3D region where the electron is most likely found (quantum model).
ψ² is called the probability density. It tells the chance of finding the electron at a given point in space.
An orbit is two-dimensional (a flat circle in one plane). An orbital is three-dimensional and has a definite shape.
It violates Heisenberg's Uncertainty Principle, because it assumes we can know the electron's exact position and speed at the same time, which is not possible.
Yes, ψ can be positive or negative because it is a wave function. But ψ² (probability) is always positive or zero.
NEET regularly gives statement-based questions mixing up ψ and ψ², and orbit and orbital. Knowing probability = ψ² and orbital = probability region wins these direct 4-mark questions.
