He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found that each element was similar to the element eight places further on.
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Why was Newland's theory criticised?
His groups contained elements that didn't have similar properties. He mixed metals and non-metals. He didn't leave gaps for elements that hadn't been discovered.
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How did Mendeleev change the periodic table?
Mendeleev put the elements in order of atomic mass, BUT found he had to leave gaps in order to keep elements with similar properties together.
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Why was leaving gaps in the table good?
They predicted the properties of so far undiscovered elements.
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What does hard water contain?
Hard water contains dissolved compounds, usually calcium or magnesium compounds.
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Which type of water forms lather with soap?
Soft water readily forms lather with soap, but it is more difficult to form lather with hard water.
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What does hard water produce?
The dissolved calcium ions and magnesium ions in hard water react with the soap to form scum.
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What is the process of Titration?
A known volume of water is put into a conical flask. Soap solution is added to it from a burette or pipette. The mixture is swirled to help it form lather. The volume of soap solution that needs to be added to form permanent lather is recorded.
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What is the difference between temporary hard water and permanently hard water?
Temporary hard water can be softened by boiling it. Permanent hard water stays hard, even when it is boiled.
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What are the advantages of hard water?
1. Can improve the taste of the water 2.Are good for the development and maintenance of bones and teeth 3. Can help to reduce heart disease
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What are the disadvantages of hard water?
1.More soap is needed to produce lather, which increases costs. This happens with temporary or permanent hardness 2.The scum produced is unsightly 3. Temporary hardness can reduce the efficiency of kettles.
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What are the two methods of softening hard water?
Adding sodium carbonate to the water and using ion exchange columns.
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How does sodium carbonate soften the water?
The carbonate ions from sodium carbonate react with the calcium and magnesium ions in the water to produce insoluble precipitates.
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How does the ion exchange column work?
The resin beads have sodium ions attached to them. As the hard water passes through the column, the calcium and magnesium ions swap places with the sodium ions.
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What is Calorimetry?
Heat energy can be given out or taken in from the surroundings during chemical reactions. The amount of energy transferred can be measured.
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Other cards in this set
Card 2
Front
Why was Newland's theory criticised?
Back
His groups contained elements that didn't have similar properties. He mixed metals and non-metals. He didn't leave gaps for elements that hadn't been discovered.
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