Bohr model and its limitations
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See all →- Energy and radius of first Bohr orbit of He^+ and Li^2+ are[Given R_H = 2.18×10^-18 J, a_0 = 52.9 pm] Answer: 1. E_n(mathrmLi²⁺) = -19.62×10⁻¹⁸ J; r_n(mathrmLi²⁺) = 17.6 pm; E_n(He^+) = -8.72×10⁻¹⁸ J; r_n(He^+) = 26.4 pm Key idea: for hydroge... 1
- The energy of an electron in the ground state (n = 1) for He^+ ion is -x J, then that for an electron in n = 2 state for Be^3+ ion in J is : Answer: 2. -x Key idea: for hydrogen-like ions E_n=-E₁(H) Z²/n² . For He^+ (Z=2), n=1: -x=-4E₀ , so E₀=x/4 . For mathrmBe³⁺ (Z=4), n=2: E=-E... 1
- If radius of second Bohr orbit of the He^+ ion is 105.8 pm, what is the radius of third Bohr orbit of Li^2+ ion ? Answer: 2. 158.7 pm Key idea: Bohr radius r_n=0.529 n²/Z Å, so r∝ n²/Z . He^+ , n = 2: r=a₀×4/2=2a₀=105.8 pm, so a₀=52.9 pm. mathrmLi²⁺ , n... 1
- Which of the following series of transitions in the spectrum of hydrogen atom falls in visible region ? Answer: 2. Balmer series Balmer series (transitions to n = 2 from n = 3, 4, 5...) lies in the visible region (about 656 to 365 nm). Lyman is... 1