Lesson test: The quantum atom

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The quantum atom

1.[2p]
Classical electrodynamics predicts that a Rutherford atom survives about $10^{- 11}$ s. What drives the collapse?

An accelerating charge radiates, and circular motion is continuous acceleration

Correct

The electron is attracted to the nucleus with nothing opposing it

The answer is: An accelerating charge radiates, and circular motion is continuous acceleration

The nucleus captures the electron by the strong force

The answer is: An accelerating charge radiates, and circular motion is continuous acceleration

Collisions with other atoms drain the orbital energy

The answer is: An accelerating charge radiates, and circular motion is continuous acceleration

2.[1p]
Before Bohr, what was the standing of the Rydberg formula?

An empirical fit of great precision with no explanation behind it

Correct

A prediction of Maxwell's equations

The answer is: An empirical fit of great precision with no explanation behind it

A rough approximation that only worked for the visible lines

The answer is: An empirical fit of great precision with no explanation behind it

A consequence of the nuclear model of the atom

The answer is: An empirical fit of great precision with no explanation behind it

3.[2p]
Using $E_{n} = - 13.6 / n^{2}$ eV, what energy in electronvolts is released when a hydrogen electron falls from $n = 3$ to $n = 2$ ?

CorrectNot quite: 1.89

4.[2p]
Which of these did the Bohr model fail to account for?

Select all that apply

The spectrum of helium

Correct

The relative intensities of spectral lines

Correct

The ionisation energy of hydrogen

The answer is: The spectrum of helium, The relative intensities of spectral lines, Why angular momentum should be quantised at all

Why angular momentum should be quantised at all

Correct

5.[2p]
De Broglie's condition that a whole number of wavelengths fits round an orbit reproduces which of Bohr's assumptions?

That angular momentum is quantised as $L = n ℏ$

Correct

That electrons in stationary states do not radiate

The answer is: That angular momentum is quantised as $L = n\hbar$

That a photon carries the energy difference between levels

The answer is: That angular momentum is quantised as $L = n\hbar$

That the orbits are circular

The answer is: That angular momentum is quantised as $L = n\hbar$

6.[1p]
In the Schrödinger picture, quantisation is postulated in the same way that Bohr postulated it.

True

The answer is: False

False

Correct

7.[2p]
Put these in the order they were proposed.

The nuclear atom
Matter waves
Quantised orbits and stationary states
The wave equation and the probability interpretation

Show the answer

a, b, c, d

1.[2p] Classical electrodynamics predicts that a Rutherford atom survives about 10-11 s. What drives the collapse?

2.[1p] Before Bohr, what was the standing of the Rydberg formula?

3.[2p] Using En=-13.6/n2 eV, what energy in electronvolts is released when a hydrogen electron falls from n=3 to n=2?

4.[2p] Which of these did the Bohr model fail to account for?

5.[2p] De Broglie's condition that a whole number of wavelengths fits round an orbit reproduces which of Bohr's assumptions?

6.[1p] In the Schrödinger picture, quantisation is postulated in the same way that Bohr postulated it.

7.[2p] Put these in the order they were proposed.

1.[2p]
Classical electrodynamics predicts that a Rutherford atom survives about $10^{- 11}$ s. What drives the collapse?

2.[1p]
Before Bohr, what was the standing of the Rydberg formula?

3.[2p]
Using $E_{n} = - 13.6 / n^{2}$ eV, what energy in electronvolts is released when a hydrogen electron falls from $n = 3$ to $n = 2$ ?

4.[2p]
Which of these did the Bohr model fail to account for?

5.[2p]
De Broglie's condition that a whole number of wavelengths fits round an orbit reproduces which of Bohr's assumptions?

6.[1p]
In the Schrödinger picture, quantisation is postulated in the same way that Bohr postulated it.

7.[2p]
Put these in the order they were proposed.