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Most alpha particles (a pair of protons and a pair of neutrons tied together by nuclear bonds - a helium nucleus) will pass right through the foil. But some will be deflected. That's because those alpha particles have electrostatically interacted with a gold atom nucleus. The gold nucleus is positively charged, and so is the alpha particle. And positive charges don't like each other. The interaction of the charges causes the alpha particles to be deflected if they approach the nucleus. If the alpha particle is on a trajectory that will take it very near (or right at) the nucleus, it will undergo proportionally more deflection, and could actually bounce back the way it came. (The technical term for this interaction is scattering.) This type of early experiment helped investigators determine that the atom had most of its mass concentrated in a nucleus. Before that, it was suspected that the particles that made up the atom were distributed within it in a "general" way. If that was true, the all the alpha particles that were shot at the foil would pass through and none would be deflected. But in the experiment, some were. Why? There must be something inside there that is big and bad and caused the alpha particles to bounce off of it. Oooo, snap! A nuclear atom with mass concentrated in the middle!
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SteveAn alpha particle changes direction when it hits gold foil because of the repulsion between the positively charged alpha particle and the positively charged nucleus of the gold atoms. As the alpha particle gets close to a nucleus, the electrostatic repulsion causes it to change direction or scatter. This experiment led to the discovery of the nucleus and revolutionized our understanding of atomic structure.
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What causes some of the alpha particles to bounce straight back from the gold foil?
Some of the alpha particles bounce straight back from the gold foil because they come very close to the densely packed positive nucleus of an atom, leading to strong repulsion due to positive charges. This results in a significant change in direction or even a complete reversal of their path.
What were The targets used in the alpha particle atomic experiments in the early 1900's?
Gold foil was typically used as the target in alpha particle atomic experiments in the early 1900s. This was famously utilized by Ernest Rutherford in his gold foil experiment to study the structure of the atom.
Why is gold foil used in the alpha particle scattering?
Gold foil is used in alpha particle scattering experiments because gold is malleable and can be hammered into a thin foil, allowing alpha particles to pass through. Additionally, gold has a high atomic number, which means it has more protons in its nucleus, making it ideal for studying the scattering of alpha particles.
The kind of particle Rutherford used to shoot through gold foil?
Rutherford shot high-energy alpha particles (two protons and two neutrons, or a helium nucleus) at the gold foil. A small fraction of these alpha particles bounced back, and that is how Rutherford discovered the nucleus.
Why did most of the alpha particles pass through the gold foil?
Most of the alpha particles passed through the gold foil because atoms are mostly empty space, and the alpha particle is small enough to pass through without colliding with the dense nucleus. This led to the discovery of the nucleus, as a few alpha particles were deflected or bounced back, indicating a dense, positively charged center in the atom.
