In the Bohr model of the hydrogen atom, the electron in the ground state (n = 1) has an orbital radius r1 and energy E1. What is the orbital radius of the electron in the n = 3 state?
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Correct answer
C. 9r1
Principle or equation
In the Bohr model, the radius of the nth orbit is proportional to n^2: r_n = n^2 r_1.
Why this answer is correct
For n = 3, r_3 = 3^2 r_1 = 9r_1.
Example
If r1 = 5.3 × 10^-11 m, then r3 = 9 × 5.3 × 10^-11 m = 4.77 × 10^-10 m.
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