Chemistry · Structure Of Atom · NEET
Psi is the wave function. It is just a mathematical function that comes out when you solve the Schrodinger equation for an electron. Its value changes depending on where the electron is (its x, y, z position). You cannot see psi in real life. By itself, psi has NO direct physical meaning. It is only a maths tool. What matters for NEET: each psi describes one orbital.
This is the most tested trap. Psi (ψ) itself has no physical meaning and can even be negative. Psi squared (ψ²) IS meaningful: it gives the probability density, meaning the chance of finding the electron at a point. So probability is proportional to ψ², NEVER to ψ. If a NEET question says 'probability is proportional to ψ', that statement is FALSE.
Because the electron behaves like a wave, not like a tiny ball moving on a fixed path (de Broglie's dual nature). Bohr's model gave the electron fixed circular orbits, but the Heisenberg uncertainty principle says we cannot know its exact path. So Schrodinger treated the electron as a wave and wrote an equation for that wave. Solving it gives allowed energy states instead of fixed orbits.
Almost. An orbital is the wave function psi for one electron. So 'orbital' and 'one-electron wave function psi' mean the same thing in this chapter. When solving the equation gives you a valid psi, that psi is called an atomic orbital. The region where ψ² is large is where the electron is most likely found.
You get two things. First, a set of allowed energy values (E) the electron can have. Second, the wave functions (psi) linked to those energies. These allowed answers automatically come with the three quantum numbers n, l and m. So the quantum numbers are NOT assumed; they fall out naturally when you solve the equation. This is a key point for NEET.
No. Psi can be positive or negative, just like the height of a wave can be above or below the line. A negative psi is normal. It does not mean negative probability. When you square it (ψ²), the sign disappears and you always get a positive probability. So a negative psi is not a problem.
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. In the light of the above statements, choose the correct answer.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Erwin Schrodinger, in 1926. He treated the electron as a wave (using de Broglie's idea) and wrote an equation for it. This started the quantum mechanical model of the atom, which replaced Bohr's model of fixed orbits.
Psi is a function, not a single number. Its value depends on where the electron is (its coordinates). At each point in space it gives one value, which can be positive, negative or zero.
Psi by itself has no direct physical meaning. But its square, ψ², tells us the probability of finding the electron at a given point. So psi is the tool, and ψ² gives the useful information.
Bohr gave the electron fixed circular paths, but the uncertainty principle says we cannot know an electron's exact position and speed together. Schrodinger's wave model uses probability instead of fixed paths, which fits real behaviour better.
Yes. When you solve the equation, only certain answers are allowed. These allowed solutions automatically bring the quantum numbers n, l and m. So the quantum numbers are natural results of the equation, not assumptions.
