Atoms as solid spheres that could be divided into smaller parts
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What is the Plum pudding model of the atom?
Sphere of positive charge with negative electrons embedded in it
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What did scientists discover in the alpha scattering experiment?
Some alpha particles were deflected by the gold foil - this showed that an atom’s mass and positive charge must be concentrated in one small space ( the nucleus)
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Describe the nuclear model of the atom?
Dense nucleus with electrons orbiting it
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What did Niels Bohr discover?
Electrons orbit in fixed energy levels (shells)
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What did James Chadwick discover?
Uncharged particle called the neutron
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Where are protons and the neutrons?
In the nucleus
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What is the relative mass of each sub-atomic particle?
Proton: 1, neutron: 1, electron: 0 (very small)
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What is the relative charge of each sub-atomic particle?
Proton: +1, neutron: 0, electron: -1
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How can you find out the number of protons in an atom?
The atomic number on the Periodic Table
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How can you calculate the number of neutrons in an atom?
mass number - atomic number
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Why do atoms have no overall charge?
Equal numbers of positive protons and negative electrons
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How many electrons would you place in the first, second and third shells?
Up to 2 in the first shell and up to 8 in the second and third shells
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What is an element?
Substance made of one type of atom
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What is a compound?
Substance made of more than one type of atom chemically joined together
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What is a mixture?
Two or more substances not chemically combined
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What are isotopes?
Atoms of the same element (same number of protons) with different numbers of neutrons
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What are the four physical processes that can be used to separate mixtures?
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Flashcard (34)