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33 Cards in this Set
- Front
- Back
Atom |
The smallest part of an element that can exist |
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Element |
Any substance made of one type of atom only |
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Compound |
A substance formed by the chemical bonding of 2 or more elements |
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Ion |
Electrically charged particle, formed when an atom or molecule gains or loses electrons. |
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What is an aqueous solution |
An aqueous solution forms when a substance dissolves in water. |
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What is a pure substance |
A substance which consists only of one element or one compound |
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Mixture |
Two or more substances that are not chemically bonded |
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Filtration |
used to separate an insoluble solid from a liquid. |
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How does filtration work effectively |
Filtration works because the filter paper has tiny holes or pores in it. These are large enough to let small molecules and dissolved
ions through, but not the much larger particles of undissolved solid. |
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Crystallisation |
The process of producing crystals from a solution by evaporating the solvent. |
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Simple distillation |
Separation method used to separate a solvent from a solution. |
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How does simple distillation work effectively |
Simple distillation works because the dissolved solute has a much higher boiling point than the solvent. When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and condensed and the remaining solution becomes more concentrated as the amount of solvent in it decreases. |
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What does fractional distillation work on |
Seperates different liquids from a mixture of liquids |
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Fractional distillation |
mixture of several substances, such as crude oil, is distilled and the evaporated components are collected as they condense at different temperatures. |
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What happens in fractional distillation when the mixture is heated |
1.vapours rise through a column which is hot at the bottom, and cooler at the top 2.vapours condense when they reach a part of the column that is below the temperature of their boiling point 3.each liquid is led away from the column |
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The 2 ways to obtain different liquids from the column in distillation |
1.by collecting different liquids from different parts of the column - the substance with the lowest boiling point is collected at the top of the column 2.by continuing to heat the mixture to increase the temperatures in the column - the substance with the lowest boiling point is collected first |
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What is chromatography used for |
Chromatography is used to separate different substances dissolved in a liquid |
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Soluble |
Able to dissolve in a solvent |
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The 2 phases of chromatography |
Mobile and stationary |
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Soluble |
Able to dissolve in a solvent |
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The 2 phases of chromatography |
Mobile and stationary |
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The chromatography stationary phase |
paper chromatography is very uniform, absorbent paper |
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Soluble |
Able to dissolve in a solvent |
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The 2 phases of chromatography |
Mobile and stationary |
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The chromatography stationary phase |
paper chromatography is very uniform, absorbent paper |
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Chromatography mobile phase |
the solvent moves through the paper, carrying different substances with it |
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What does a chromatogram show |
The results of separating mixtures by chromatography. |
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How to know something is a pure substance on a chromatogram |
a pure substance produces one spot on the chromatogram |
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How to know if something is an impure substance on a chromatogram |
an impure substance, or mixture, produces two or more spots |
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How to know if 2 substances are likely the same using a chromatogram |
1.they produce the same number of spots, and these match in colour 2.the spots travel the same distance up the paper |
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Who published the first organised periodic table |
Dmitri Mendeleev |
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2 features of Mendeleev’s periodic table |
1.had gaps in it 2.showed elements with similar chemical properties lined up in groups |
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What did Mendeleev do about undiscovered elements and how did he fit them in the organised system |
Mendeleev left gaps in his table for elements not known at the time. By looking at the properties of the elements next to a gap, he could also predict the properties of these undiscovered elements. |