Edexcel Chemistry IGCSE

Atom  -  the smallest particle of a chemical element that can exist. Molecule  -  a group of  atoms   bonded  together, representing the  smallest fundamental unit of a chemical compound  that can take part in a  chemical reaction.

PAPER CHROMATOGRAPHY Diagram Showing the Paper Chromatography of Ink and Plant Dye USE: To Separate Substances that have Different Solubilities in a Given Solvent (E.g Different Coloured Inks that have been Mixed to Make Black Ink) METHOD: Pencil Line is Drawn on Chromatography Paper and Spots of Ink / Dye is Placed on it Paper is Lowered into a Bucket of Solvent, Allowing the Solvent to Travel Up the Paper, Taking some of the Coloured Substances with it Allow Chromatography to Occur until the Solvent Reaches the Top of the Paper RESUTS: As the Solvent Travels Up the Paper, Different Substances will have Different Solubilities so will Travel at Different Rates, Causing the Substances to Spread Apart This will show the Different Components of the Ink / Dye - http://igcse-chemistry-2017.blogspot.ae/2017/07/113-practical-investigate-paper.html

R f VALUES: Used to Identify the Components of Mixtures s The R f value of a particular compound is always the same →This allows industries to use chromatography to identify the compounds in a mixture. EQUATION : s Rf Value =     Distance Moved by Compound    ÷     Distance Moved by Solvent