Atoms NEET MCQs

Atoms NEET MCQs - Important Formulae

• Bohr angular momentum: mvr = nh / (2 pi)
• Bohr radius: r_n = a0 n² / Z, where a0 = 0.529 A
• Velocity in nth orbit: v_n = (2.18 x 10⁶) Z / n m s^-1
• Energy of hydrogen-like atom: E_n = -13.6 Z² / n² eV
• Ionisation energy: IE = 13.6 Z² / n² eV
• Kinetic and potential energy: KE = -E_n, PE = 2E_n, Total energy = -KE
• Time period: T_n = T0 n³ / Z², T0 approx 1.52 x 10^-16 s
• Orbital frequency: f_n = 1 / T_n
• de Broglie condition: 2 pi r = n lambda
• de Broglie wavelength: lambda = h / p = h / mv
• Hydrogen spectrum: 1 / lambda = R Z² (1 / n1² - 1 / n2²)
• Spectral lines: Number of lines from level n = n(n - 1) / 2
• Closest approach: r0 = (1 / 4 pi epsilon0) (2Ze²) / K_alpha
• Rutherford scattering: N(theta) is proportional to 1 / sin⁴(theta / 2)
• X-ray cutoff wavelength: lambda_min = hc / eV = 12400 / V A
• Moseley law: sqrt(nu) = a(Z - b), and for K-alpha approximately nu proportional to (Z - 1)²
• Photon energy: E = h nu = hc / lambda
• Momentum of photon: p = h / lambda
• Atomic radius trend for hydrogen-like ions: r is proportional to n² / Z
• Laser condition: Population inversion is required for stimulated emission