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Rutherford's gold foil experiment

Hi I need help on the following question about Rutherford’s gold foil experiment:

Comment on the possible changes in his experimental observations if he had used Lithium foil, 7Li, instead of gold

I have another question:

Radon emits alpha particles. Radon can be held in the hand without any harm. If it is inhaled it is very dangerous. Explain why.

I have another question:

Explain why small doses of gamma radiation are less harmful than small doses of beta radiation, even though gamma radiation is more penetrating.

Hi Gary,

Thanks for your questions.

Rutherford needed to use gold foil that was very thin so that the alpha particles that were fired at it could pass through unless they were deflected by positive charges. If the foil was thick then the alpha particles would have to penetrate through many layers of gold atoms and were more likely to be deflected as they penetrated through the many layers. The gold foil Rutherford used was as thin as possible. This allowed most alpha particles to pass through and only some were deflected a little, with a very few being deflected straight back.

If Li could be rolled out as thinly then the results would be similar. This would be challenging and probably very expensive. The scattering angles may be different since the nucleus of Li only contains 3 protons – gold is much heavier and can more easily scatter an alpha particle. It might be that the small size of the Li nucleus might affect the deflection of the alpha particles.

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Radon is a gas a room temperature so can’t be held in the hand (although it is very dense!). Radon is produced when radium decays. When radon decays it emits alpha particles which cause damage to the DNA of cells (especially of the cells in the lining of the respiratory system).

If radon could be held in the hand, the alpha particles can’t penetrate the skin to do any damage. They need to be inhaled or ingested and then they are dangerous.

Gamma radiation is highly penetrating, but the least ionising of the three main types of radiation, and therefore does the least damage to cells. Beta particles do pass through the skin but only travel a few cm into the body tissue before they lose all their energy (they are more dangerous when inhaled or ingested). Beta particles obviously have mass and charge, and are more ionising than gamma radiation, but less than alpha, therefore if they pass into the body they will do more damage to the cells than the equivalent dose of gamma.

Hi Monique, thank you so much for answering my questions, but I have another question, it would be great if you can answer this asap:

The half-life of Strontium 90 is about 29 years and it decays into Yttrium 90.

Yttrium 90 is also radioactive and is a beta particle emitter with a half-life of 2.67 days.

Discuss the amount of Yttrium that would be present in the above example after the Strontium had been decaying for the first 8 days.

Jason drops a leaf into the water. (The leaf is lighter than the stone.) How will the velocity of the leaf compare with the velocity of the stone when it hits the water? Compare the acceleration of the leaf and the stone as they fall from rest.

Bob is at the start of his 100m sprint race. He is at rest and, at the firing of the starting gun he accelerates for 6.0 s up to his sprinting speed. He travels 25 m while accelerating.

a. Calculate Bob’s acceleration. Give your answer to the correct number of significant figures.