Radioactivity levels 7-9

Question 1

Explain why alpha decay causes an atom to change into a different type of atom

Answer 1

When something decays by alpha decay, it looses two protons and two neutrons. This causes the atomic number to reduce by two, and when the atomic number changes so does the type of atom that it is.

Question 2

Explain why beta particle radiation causes an atom to change into another type of atom

Answer 2

When an atom decays by beta particle decay it causes a neutron in the nucleus to change into a proton. This increases the atomic number by one, and when the atomic number changes so does the type of atom that it is.

Question 3

Explain why an atom does not change into a different type of atom when gamma radiation is emitted

Answer 3

Gamma radiation emission does not change the number of protons or neutrons in the atom. As the atomic number stays the same, so does the type of atom that it is.

Question 4

Visible light and gamma radiation are both electromagnetic waves. Compare the differences and similarities between the two.

Answer 4

Similarities

They both travel at the speed of light (3x10⁸ m/s)

They can both travel through a vacuum

Differences

Gamma is ionising and visible light is not

Gamma radiation has a higher frequency and a shorter wavlenegth

Gamma radiation can pass through many materials that visible light cannot (such as paper)

Question 5

Explain why JJ Thompsons plum pudding model was replaced by Rutherfords nuclear model

Why was Rutherford model then replaced by the Bohr model

Answer 5

The nuclear model replaced the plum pudding model because of evidence that could not be explaind by the plum pudding model. The results of the rutherford scattering experiment would not have occured as a result of the plum pudding model so a new model was created.

It was then discovered that atoms gave off certain wavelengths of light as they cooled down. This could not be explained by the plum pudding model so a new model, the Bohr model, with electrons orbiting in specific electron shells was created to explain this.

Question 6

Why is radiation emitted from the nucleus of an atom?

Answer 6

Radiation is emitted from the nucleus of an atom becuase some isotopes have an unstable balance of protons and neutrons. It decays by radioactive decay in order to create a more stable balance of protons and neutrons.

Question 7

Write a decay equation to describe how Astatine (At, mass number 213 atomic number 85) decays by alpha decay.

Explain how you did this

Answer 7

To write the equation first you know that alpha decay is the same as a helium nucleus with a mass number of 4 and an atomic number of 2. Then you need to make sure that the total of the atomic numbers on each side are the same and the total of the mass numbers on either side are the same.

Question 8

Write a decay equation to show the decay of lead (Pb, 214 neutrons and 82 protons) to Bismuth (Bi)

Explain how you did this

Answer 8

First you know that beta radiation is one electron with an atomic number of -1 (becuase it has a charge of -1)

Then you need to make sure that the total atomic number is the same on both sides and the total mass number is the same on both sides.

Question 9

Explain how radiation can be used to monitor the thickness of paper that is being manufactured

Justify which type of radiation is used for this purpose