Chemistry year 11 Syllabus Summary

Essay by lil_azn77High School, 11th grade April 2007

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Module 1: The chemical Earth1. The living and non-living components of the Earth contain mixturesIdentify the difference between elements, compounds and mixtures in terms of particle theory•Homogenous means of uniform composition throughout, for example pure water, sugar, aluminium, petrol or whisky. Heterogeneous means having non-uniform composition where we can recognise small pieces of the material which are different from other pieces, for example strawberry jam, wood, or water with ice in it.

•An impure substance is one substance contaminated with small amounts of one or more other substances. An impure substance is therefore a mixture.

•An element is a pure substance which cannot be decomposed into simpler substances. Some common elements are aluminium. Carbon (diamond) and oxygen.

•A compound is a pure substance which can be decomposed into simpler substances, for example into elements. Some common compounds are table salt (sodium chloride), sodium carbonate (washing soda).

•In solids, particles are packed closely together.

There are strong forces holding the particles to one another which cause solids to have definite shapes and to be relatively hard. In solids particles vibrate slightly above their rest positions.

•In liquids, particles move about much more freely. Particles in liquids possess more motion - more kinetic energy - and the forces between neighbouring particles are comparatively weaker than in solids. Therefore liquids do not have definite shapes but instead take the shape of the container they are placed in. Solids have greater density than liquids because the particles are packed more closely together in solids.

•In gases, the particles are much further apart than in solids or liquids, and they are in very rapid random motion. The particles are so far apart and moving so rapidly that there are no significant forces between them. Because the particles are in such rapid random motion, gases quickly...