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ELEMENTS, ACIDS AND WATER
The Periodic Table:
Early 1800's: only went on atomic mass.
Newlands Law of Octaves (1864) ­ every 8th element with similar properties. Pattern failed in 3rd row
due to transition metals. Criticised as - He left no gaps. ­groups contained some not similar ­ Mixed
metals…

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These were accepted as it explained acid behaviour. Also it was adaption of already working idea.
IN ACIDIC SOLUTIONS: acid molecules dissociate to release H+ ions, which then become hydrated.
IN BASIC SOLUTIONS: water molecules dissociate into H+ and OH-, but some take hydrogen ions,
leaving excess OH-. Other beses…

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ENERGY AND CHEMICAL TESTS
Energy:
Exothermic ­ gives out energy to surroundings, normally in heat form and rise in temp.
Endothermic ­ the opposite!
Measure energy produced by temp before and after. Large amount of energy lost to surround :/
reduce by putting cup in cotton wool as insulation.
Energy…

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Experimental mass
Divide that mass by the relative atomic mass.
Ratio.

Instrumental methods:
faster, accurate, technicians, not chemists. expensive.
Atomic Absorption Spectroscopy ­ metals. Recognises pattern.
IR Spectrometry ­ pattern of absorbance is unique.
UV spectrometry.
NMR spectroscopy ­ ORGANIC COMPOUNDS, what atoms hydrogen connects to.
Gas-liquid chromatography.
Mass Spectrometry.

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