C1 atomic structure Flashcards
what is an atom
All substances are made of atoms. An atom is the smallest part of an element that can exist.
what is an element
an element is a substance which only contains one type of atom
what is a compound
a compound is a substance which contains atoms from 2 or more elements which are chemically combined in fixed proportions
what is the charge of protons
+1 they are positively charged
what is the charge of electrons
-1 they are negatively charged
what is the charge of neutrons
0 they are neutral
what is a mixture
two or more elements or compounds not
chemically combined together
what is filtration
Filtration is used to separate an insoluble solid from a liquid. It is useful for separating sand from a mixture of sand and water, or excess reactant from a reaction mixture.
what is crystallization
Crystallisation is used to produce solid crystals from a solution. When the solution is warmed, some of solvent evaporates leaving crystals behind. For example, crystallisation is used to obtain copper sulfate crystals from copper sulfate solution.
how do you separate a mixture using crystallization
put the solution in an evaporating basin
warm the solution by placing the evaporating basin over a boiling water bath
stop heating when crystals begin to form around the edge of the basin
what is simple distillation
Simple distillation is used to separate a solvent from a solution
how does simple distillation work
Simple distillation works because the dissolved solute has a much higher boiling point than the solvent.
When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and condensed.
The remaining solution becomes more concentrated as the amount of solvent in it decreases.
what is fractional distillation
Fractional distillation is used to separate different liquids from a mixture of liquids.
what is chromatography
Paper chromatography is used to separate mixtures of soluble substances. These are often coloured substances such as food colourings, inks, dyes or plant pigments.
what were atoms originally thought to be
Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided.