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smallest particle of an element |
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positively charged particles inside the nucleus |
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specific amount of energy it has; an electron's movement is related to its energy level |
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electrically neutral particle |
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atoms with the same number of protons and different number of neutrons |
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the sum of the protons and neutrons in the nucleus of an atom |
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unique number of protons in the nucleus of an atom |
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negatively charged particles |
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What is the atomic theory? |
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Grew as a series of models that developed from experimental evidence. As more evidence was collected, the theory and models were revised. |
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How was Chadwick's atomic model different from those in the past?
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The modern model describes an atom as consisting of a nucleus that contains protons and neutrons, surrounded by a cloudlike region of moving electrons. **Chadwick founded the neutron; neutrons were hard to detect before this because they had almost the same mass as a proton |
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Explain Dalton's Atomic Theory. (4 steps) |
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1) All elements are composed of atoms that cannot be divided
2) All atoms of the same element are exactly alike and have the same mass. Atoms of different elements are different and have different masses.
3) An atom of one element cannot be changed into an atom of a different element. Atoms cannot be created or destroyed in any chemical change, only rearranged.
4) Every compund is composed of atoms of different elements, combined in a specific ratio. |
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Where were the electrons located in Thomson's model of an atom? |
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Thomson said that electrons were scattered throughout the atom all over the place (like blueberries in a muffin) |
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Bohr's model is different from Thomson's; Bohr said that electrons could only have certain orbits. Electrons moved like planets orbiting the sun in his model (or like layers of an onion) |
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Where were the electrons located in the modern model of the atom? |
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The modern model of an atom has a nucleus that contain protons and neutrons, surrounded by a cloudlike region of moving electrons. |
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