The Nuclear Model of the Atom (Cambridge (CIE) O Level Physics): Exam Questions

This notation represents the nucleus of a neutral atom of carbon-14.

State the number of: 

(i) protons in the nucleus of an atom of carbon-14

[1]

(ii) electrons orbiting the nucleus of an atom of carbon-14

[1]

(iii) neutrons in the nucleus of an atom of carbon-14.

[1]

Carbon-14 is an isotope of carbon. Carbon-12 is another isotope of carbon.

Compare the nucleus of carbon-14 with the nucleus of carbon-12.

State the similarities and differences.

Scientists use carbon-14 to estimate the age of wood that is very old.

A very old sample of wood contains 1.0 × 10⁸ carbon-14 atoms.

When the sample was new, it contained 8.0 × 10⁸ carbon-14 atoms. The half-life of carbon-14 is 5700 years.

Estimate the age of the sample of wood.

age of wood = ........................... years 

Use words from the box to complete the sentences about the charges in an atom. Words can be used once, more than once or not at all. 

The charge on the nucleus of an atom is ......................................

The charge on a proton is ..............................................

The charge on electrons orbiting the nucleus is .............................

A nucleus of radium-226 has the nuclide notation shown.

(i) Determine the number of protons in a nucleus of radium-226.

[1]

(ii) Determine the number of neutrons in a nucleus of radium-226.

[1]

(iii) Radium has another isotope, radium-223.

Write the nuclide notation for radium-223.

[1]

Radium-226 has a half-life of 1600 years.

A sample contains 8.0 mg of radium-226.

Calculate the time for the sample to decay until only 1.0 mg of radium-226 remains.

   time = ............................................... years 

A nuclear power station uses uranium to generate thermal energy.

The fuel for the power station is an isotope of uranium.

Explain the meaning of the term isotope.

When the nucleus of one particular isotope of uranium decays, it releases a β-particle. In the periodic table the entry for this isotope looks like this:

State the proton number, the mass number and the neutron number of this isotope.

A sample of rock includes some uranium-239.

The half-life of uranium-239 is 23 minutes.

Determine the fraction of the uranium-239 that remains after 46 minutes.

fraction remaining = ...........................................................

The circles shown in Fig. 11.1 represent three gold nuclei. Three α-particles are approaching the gold nuclei.

On Fig. 11.1, complete the path of each α-particle.

The isotope hydrogen-1 has a proton number of 1 and a nucleon number of 1.

Two isotopes of helium are helium-3 and helium-4.

Helium-3 has a proton number of 2 and a nucleon number of 3.

Helium-4 has a nucleon number of 4.

Complete Table 11.1 for neutral atoms of these isotopes of helium.

This notation represents the nucleus of a neutral atom of carbon-14.

State the number of: 

(i) protons in the nucleus of an atom of carbon-14

[1]

(ii) electrons orbiting the nucleus of an atom of carbon-14

[1]

(iii) neutrons in the nucleus of an atom of carbon-14.

[1]

Carbon-14 is an isotope of carbon. Carbon-12 is another isotope of carbon.

Compare the nucleus of carbon-14 with the nucleus of carbon-12.

State the similarities and differences.

Scientists use carbon-14 to estimate the age of wood that is very old.

A very old sample of wood contains 1.0 × 10⁸ carbon-14 atoms.

When the sample was new, it contained 8.0 × 10⁸ carbon-14 atoms. The half-life of carbon-14 is 5700 years.

Estimate the age of the sample of wood. 

age of wood = ........................... years

Table 1.1 shows data about nine elements.

Table 1.1

Carbon-14 is a radioactive isotope with a nucleon number of 14. It decays by emitting β-particles.

Use data from Table 1.1 to write down the nuclide equation for this decay.

A radioactive sample is placed close to a detector. The radioactive isotope in the sample has a long half-life. The detector records a count rate of 597 counts/s.

Fig. 11.2 shows the readings when different materials are placed between the radioactive sample and the detector.

 Fig. 11.2

Explain whether any α-particles, β-particles or γ-rays are emitted by the radioactive sample.

Fig. 10.1 represents a neutral atom of an isotope of element X.

State one similarity between this atom and a neutral atom of a different isotope of element X.

The isotope of element X is radioactive. It decays to form an isotope of element Y by emitting a β-particle. 

(i) Using Fig. 10.1 deduce the nuclide notation for the isotope of Y produced by this decay.    

nuclide notation:  [3]

(ii) β-particles ionise the air they pass through less strongly than the same number of α-particles.

Suggest why this is so.

[3]

A radioactive nucleus of carbon decays to a nucleus of nitrogen by emitting a particle.

Complete the nuclide equation and state the name of the particle.

A radioactive substance decays by emitting an α-particle.   

The nuclide notation for an α-particle is   

(i) State the term given to the number 4, written in the nuclide notation.

[1]

(ii) State the term given to the number 2, written in the nuclide notation.

[1]

Astatine-210 is a radioactive material. The nucleus of astatine can be represented by the symbol shown.

Complete the table to describe the nucleus of astatine-210.