chemistry flashcards unit 1

definition of an atom

smallest part of an element - cannot be chemically split into smaller parts

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definition of an element

substance made fron only ONE type of atom, listed in the periodic table

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definition of a compound

a substance made from two or more atoms or elements CHEMICALLY joined

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name the four signs of a chemical reaction in order of significance

new product formed, heat energy change, effervescence, colour change.

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definition of a mixture

two or more elements or compounds not chemically joined

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6 steps in the scientific model

scientists come up with idea, experimental data tested against the idea, publish their idea and results to other scientists, other scientists test the experiments anad modify the idea, publish the repeats of the results, consensus formed

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name souces of scientific publication

scientific journal, confrences, scientific websites,

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diatomic elements

I Br-ing Cl-ay F-or O-ur N-ew H-ouse

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why are mixtures easy to seperate

you can seperate them without a chemical reaction by exploiting the physical differences between the 'components'

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name the five methods for seperating mixtures

filtration, distillation, fractional distillation, crystalisation, chromotography

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what is filtration used to seperate

insoluble solid from a liquid

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what is distillation used to seperate

a solvent from a solution

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what is fractional distillation used to seperate

two liquids with different boiling points

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what is crystalisation used to seperate

a soluble solid from a liquid

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what is chromotography used to seperate

complex mixtures

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examples of each of the types of mixture sperated in the five ways

sand and water - filtration; salt and water - crystalisation; ethanol and water - distillation; crude oil - fractional distillation; salivia - chromotography

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how to produce a pure dry insoluble solid from filtration

using filter paper filter the solution and collect the wet precipitate, wash with clean solvent to remove any soluble impurities then air or low temperature oven dry

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how does simple distillation seperate a solvent from a solution

heat the solution in a distiallation flask - the liquid will boil vapour rises into the condenser liquid condensed and collected if water 100degreesC

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how does fractional distillation sperate liquids with different boiling points

mix of liquids is heated, vapours rise up fractionating column and fall back down when the tempertature ther is < their bp until the temp at the top is their bp then this liquid with the lowest bp is condensed,collected other ls collected dif stages

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how crystalisation gets a pure dry soluble solid from solution

dissolve sample in water heat solution until most of the water is evaporated off and small crystals begin to form, hot filter to remove insoluble impurities, cool at room temp, cold filter to remove soluble impurities wash with cold solvent air dry

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how chromotography seperates complex mixtures*

2 phases, the stationary phase mobile phase when a solvent is added The different dissolved substances in a mixture are attracted to the two phases in different proportions. This causes them to move at different rates through the paper in this case.

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chemistry flashcards unit 1

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