C1 - atomic structure Flashcards
how many elements are there
around 100
what do the symbols in the periodic table represent (e.g. Mg, O, Na)
the different elements
how is the periodic table organised
in groups (columns)
what are the elements that lie next to the step line called
metalloids
what are word equations used for
to see which substances are used
what are symbol equations used for
to show how much of each substance is involved
what is the law of conservation of mass
the total mass of products formed in a reaction is equal to the total mass of the reactants
balance H2 + O2 -> H2O
2H2 + O2 -> 2H2O
what are the separation techniques
filtration
crystallisation
distillation
chromatography
what is filtration used for
separating substances that are insoluble in a particular solvent from those that are soluble in the solvent
what is crystallisation used for
separating a soluble solid from a solvent, e.g. obtaining a salt from a salt solution
what is distillation used for
collecting the solvent
how does fractional distillation work
by using a fractionating column containing glass beads, you boil the miscible liquids, the substances with the higher boiling point will condense more readily on the cooler glass beads at the bottom and drip down into the flask beneath, the lower boiling point substances will continue rising and pass into the condenser
what is paper chromatography used for
separating (and identifying) substances from mixtures in a solution
describe the process of chromatography
a capillary tube is used to dab a spot of the solution on a pencil line near the bottom of a sheet of chromatography paper. the paper is then placed standing in a solvent at the bottom of a beaker. the solvent is soaked up through the paper running through the spot of the mixture.
