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#atomic stability

2 public questions tagged with this topic.

Atomic Models - Rutherford, Thomson and Bohr

Why did Rutherford’s nuclear model fail to explain the stability of atoms?

**Thomson's plum pudding model** positive charge uniformly distributed in sphere with electrons embedded, positive charge spread, fails to explain large angle scattering observed. Bohr's model introduces stationary orbits with quantized angular momentum L = n h/2π, physical basis de Broglie standing wave condition 2πr = n λ, circumference fits n wavelengths, explains line spectrum. In classical theory, an accelerating electron (in circular orbit) emits radiation, losing energy and spiraling into the nucleus, contradicting atomic stability. Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R =

Ref: NCERT > Physics Book > Atoms and Nuclei > Atomic Models - Rutherford, Thomson and Bohr

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Atomic Models - Rutherford, Thomson and Bohr

Why does the classical electromagnetic theory predict that an atom should collapse?

**Rutherford's nuclear model** atom has small massive positively charged nucleus with electrons orbiting, size ratio atomic to nuclear ~10⁵, nucleus ~10⁻¹⁵ m atom ~10⁻¹⁰ m, most alpha particles with large impact parameter pass undeflected, small fraction >90° scatter from close approach, centripetal force provided by Coulomb attraction k Z e²/r², fails to explain stability because accelerating charge should radiate and collapse. An accelerating electron in orbit emits radiation, losing energy and spiraling into the nucleus, leading to collapse according to classical theory. Using E_n = -13.6/n

Ref: NCERT > Physics Book > Atoms and Nuclei > Atomic Models - Rutherford, Thomson and Bohr

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