Degrees of freedom of a diatomic moleculeद्विपरमाणुक अणु की स्वातंत्र्य कोटियाँ

NCERT Fig 12.5–12.6 · interactive diagram

Parts and their functions

• 3 translational degrees of freedom (3 स्थानांतरीय स्वातंत्र्य कोटियाँ) — Motion of the centre of mass along x, y, z: each gets ½k_BT.
• 2 rotational degrees of freedom (2 घूर्णी स्वातंत्र्य कोटियाँ) — Rotation about the two axes perpendicular to the bond; rotation about the bond itself has negligible moment of inertia.
• Vibrational mode (कंपन विधा) — Atoms oscillate along the bond: kinetic + potential terms, so k_BT per mode. Active only at high temperature (e.g. Cl₂ partly at room T).
• Bond (rigid rotator model) (आबंध (दृढ़ घूर्णक मॉडल)) — Rigid diatomic: 5 degrees of freedom ⇒ U = (5/2)RT, C_v = (5/2)R, γ = 7/5.
• Two atoms (दो परमाणु) — Each atom alone (monatomic gas) would have only 3 translational degrees: C_v = (3/2)R.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 12.5–12.6. Report a mistake