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Question 18M.2.HL.TZ2.9b

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.2.HL.TZ2.9b
Level HL Paper 2 Time zone TZ2
Command term Outline Question number b Adapted from N/A
b.
[Maximum mark: 3]
18M.2.HL.TZ2.9b
(b)

Bohr modified the Rutherford model by introducing the condition mvr = n h 2 π . Outline the reason for this modification.

[3]

Markscheme

the electrons accelerate and so radiate energy

they would therefore spiral into the nucleus/atoms would be unstable

electrons have discrete/only certain energy levels

the only orbits where electrons do not radiate are those that satisfy the Bohr condition «mvr = n h 2 π »

[3 marks]

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