Term
| Describe the structure of an alpha particle in as much detail as possible. |
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Definition
| An alpha particle can be described as either the nucleus of a Helium atom or as 2 protons and 2 neutrons joined together. |
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Term
In Rutherford's famous experiment most of the alpha aprticle went straight through the thin piece of gold film in a straight line. What did Rutherford learn about the structure of the atom from this? |
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Definition
| The fact that so many alpha particles went straight through means that the vast majority of an atom must be empty! |
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Term
In Rutherford's famous experiment some of the alpha particles went through the thin piece of gold film but were also deflected (changed direction). What did Rutherford learn about the structure of the atom from this? |
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Definition
| The positively charged alpha particles were being repelled by something which was also positively charged (we now call this the nucleus) |
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Term
In Rutherford's famous experiment very few of the alpha particle actually were reflected blackwards of the gold film in a straight line. |
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Definition
The alpha particles were colliding with something which was a. Very dense because they reflected back off it. b. something very small because it did not happen very often. Rutherford had discovered the nucleus! |
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Term
| Describe the structure of an atom in as much detail as possible. |
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Definition
At the centre of an atom is a very small, very dense and positively charged region called the nucleus. This contains particles called protons and neutrons. Orbitting the nucleus are much smaller particles called electrons, they exist in things called shells. |
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Term
| Describe the mass and electric charge properties of electrons, protons and neutrons. |
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Definition
Protons and neutrons have roughly the same mass (neutrons are slightly heavier), electrons have about 1/2000 of the mass of a proton or neutron. Protons have positive charge. Electrons have negative charge. Neutrns are neutral, they have no charge. |
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Term
| What does the mass or nucleon number tells us about the structure of a nucleus? |
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Definition
| The mass or nucleon number is the total number of protons and neutrons in the nucleus. |
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Term
| What does the atomic number tells us about the structure of the nucleus? |
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Definition
| THe atomic number is the number of protons found in the nucleus. |
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Term
| How can you work out the number of neutrons found within the nucleus? |
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Definition
| Subtract the atomic number from the mass number. |
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Term
An atom is neutral so what does this tell you about the number of protons and electrons? |
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Definition
| There must be an equal number of protons and electrons so that the negative charge cancels out the positive charge to make the atom neutral. |
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Term
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Definition
An ion is an atom which has gained or lost electrons. This makes the atom either positively charged (if it lost an electron) or negatively charge (if it gained an electron). |
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Term
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Definition
Isotopes are atom which have the same number of protons but different numbers of neutrons. For example Carbon 12 has 6 protons and 6 neutrons Carbon 13 has 6 protons but 7 neutrons Carbon 14 has 6 protons but 8 neutrons. They are all isotopes. |
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Term
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Definition
| A very fast moving (high amount of kinetic energy) electron. |
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Term
| Where do alpha particles, beta particles and gamma rays come from? |
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Definition
They are all emitted from an unstable nucleus of an atom. |
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Term
| What will happen to the mass and atomic number if an alpha particle is emitted? |
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Definition
An alpha particle is made up of 2 protons and 2 neutrons. Therefore the mass number will go down by 4 and the atomic number by 2, an atom of a new element will have been formed. |
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Term
| What will happen to the mass and atomic number if a beta particle is emitted? |
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Definition
If a beta particle is emitted from the nucleus then a neutron has changed into a proton and electron (the beta particle). Therefore the atomic number will have gone up by one, the mass number will stay the same. An atom of a new element will have been formed. |
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Term
| What will happen to the mass and atomic number if a gamma ray is emitted? |
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Definition
A gamma ray is pure energy. Nothing will have happended to the neutrons and protons in the nucleus other than they have lost some energy. Therefore the mass and atomic number stay the same. |
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