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GCSE Chemistry: Atomic Structure (Keywords (Atom: The smallest particle…
GCSE Chemistry:
Atomic Structure
Keywords
Atom
: The smallest particle of an element
Molecule
: Multiple atoms chemically bonded together.
Element
: A substance made of one type of atom
Compound
: A substance made from different kinds of atom chemically bonded together.
Mixture
: Two or more substances mixed together, but not chemically bonded.
Isotope
: Atoms of the same element but with different numbers of neutrons.
The law of conservation of mass
: In a reaction, the atoms are rearranged into compounds, so mass is never gained or lost in a chemical reaction
The History of the Atom
Initially, people believed atoms where tiny spheres, the smallest thing possible.
When the electron was discovered, the plum pudding model was created, which showed the atoms as solid spheres of positive charge with negative electrons embedded in them.
The alpha scattering experiments proved the plum pudding model wrong, replacing it with the nuclear model, which showed a small positively charged nucleus surrounded by electrons orbiting in shells. Later experiments led to the discovery of neutrons and protons.
The Structure of an Atom
Protons
+1 Relative Charge
1 Relative Mass
Neutrons
0 Relative Charge
1 Relative Mass
Electrons
-1 Relative Charge
Virtually no Relative Mass. There is some, but it is so little that is doesn't count.
Separating Mixtures: Methods
Filtration
: Use a filter to separate an insoluble solid from a liquid.
Crystallisation
: Evaporate the liquid away to leave soluble solids crystals behind.
Simple Distillation
: Heat a solution to evaporate it, then condense the liquid for collection.
Fractional Distillation
: Using a fractionating column, separate liquids from a solution based on boiling points.
Chromatography
: Separate soluble substances from each other.
