Chemistry - Development of the Periodic Table

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What were the Dobereiner triads?
In 1829, Dobereiner noticed that sometimes three elements had three similar properties.
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Name a Dobereiner triad.
(Lithium + sodium + potassium)(calcium + strontium + barium)(chlorine + bromine + iodine)
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What was the law of octaves?
Discovered by John Newland, when elements were put in order of atomic weight there was a pattern of similar properties every eight elements.
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How did Mendeleev originally organise the elements?
In order of atomic weight.
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Explain the process Mendeleev went through to organise the elements.
He swapped them around so that the chemical behaviour patterns fitted better. He was able to imagine the existence of undiscovered elements and left gaps in his table for these to fit into.
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What did Mendeleev call the undiscovered elements:
He put the the prefix 'eka' in front of the element above the undiscovered element.
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How did the discovery of Germanium support Mendeleevs approach?
He had predicted that an undiscovered element would soon be discovered and fit into that place. That was proved right when Germanium was discovered as that was the element that fit into the gap
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Why was the order based on atomic weight incorrect?
Due to the existence of isotopes.
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Other cards in this set

Card 2

Front

Name a Dobereiner triad.

Back

(Lithium + sodium + potassium)(calcium + strontium + barium)(chlorine + bromine + iodine)

Card 3

Front

What was the law of octaves?

Back

Preview of the front of card 3

Card 4

Front

How did Mendeleev originally organise the elements?

Back

Preview of the front of card 4

Card 5

Front

Explain the process Mendeleev went through to organise the elements.

Back

Preview of the front of card 5
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