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Particulate Nature of Matter
In the I/GCSE chemistry curriculum, there are some highlight:
- Solids - fixed volume, vibrate about a fixed point, strong intermolecular attractions.
- Liquids - Weaker attractive forces, Take the volume of the container, slide.
- Gases - almost no intermolecular forces, move around quickly, collide frequently.
- Interconversions - Condensation/Freezing (solidifacation) - particles lose KE so when collide they cannot bounce again, so take up a more fixed point. Evaporation,Boiling - Gain KE so particles move more quickly, lose their fixed shape.
- Diffusion - the spreading out of particles from an area of high concentration to an area of low concentration- affected by lighter/heavier particles, higher temperature particles diffuse faster.
- Evidence for diffusion - in gases spread across - bromine gas. Liquids- liquids and solutions travel up the liquids.
Experimental Techniques
- Time - Stopwatch/Clock
- Mass - Balance
- Temperature -Thermometer
- Volume - Measuring cylinder, beaker, Burette, Pipette,Gas syringe
- Purity - Chromatography with use of solvent, penciled line, coloured substance- a dot of the coloured substance is placed on a pencilled line with the solvent level below the line. The ink would gradually spread out creating different coloured inks on the paper that can be compared to other substances to see if a substance is pure or contains other substances. You could also check the boiling/melting point of a substance to compare to those with set bp/mp , if there is a bigger change it means there are more impurities. This is very important in foodstuffs/drugs to check if they are pure and safe to use.
- Other purification techniques - Filtration (to separate an insoluble solid from a luquid), Crystallisation (to separate a soluble solid from a liquid with different bp), Simple Distillation (to separate liquids that have significantly different bp) and Fractional Distillation (liquids that have close range bp) - Fractional column - separating petroleum.
Atoms/Elements/Compounds
Conditions in the I/GCSE chemistry curriculum:
- Proton - (+1), mass of 1
- Neutron - (0) mass of 1
- Electron - (-1) mass of 1/1840
- Proton number - number of protons present in the nucleus of an elemnt, Nucleon number-number of protons and electrons present in a nucleus of an atom.
- Isotopes - same amount of protons and electrons, different amount of neutrons - non-radioactive/radioactive, radioactive isotopes used in medicine to sterilise medical eqeuipment,radiotherapy and industrial in to detect leaks by adding to oil/natural gas and using GM tube to check.
End of this topic!
