Elements, Compounds and Mixtures

• A pure substance contains only onetype of matter in that it can be asingle element or compound.
• Pure substances have a fixed,definite set of properties.
• Pure substances are mostly homogeneous in nature


  containing only one type of atom or molecule.These substances mainly have a constant or uniformcomposition throughout.The substances have fixed boiling and melting points.
• Impurities will cause a pure substanceto boil over a wide temperature rangeor raise the boiling point/ lower themelting point or cause it to melt over awider temperature range.
• Elements cannot be broken down by chemicalmeans
• Compounds have two or more elements chemicallycombined
• A mixture is the physical combination oftwo or more pure substances.
• As chemical bonding does not take placewithin a mixture, the components can beseparated by physical means such as theirsolubility, boiling point and melting points.
• Homogeneous means it consists of the same composition and uniform appearance throughout
• A mixture in which a solute (solid, liquid, gas) dissolvescompletely in a solvent (usually a liquid; can be a gas orsolid).
• Saturated Solution is a solution that contains the maximumamount of solute that is capable of being dissolved.
• A solute is a substance that is dissolved in a solvent.
• A solvent is a substance that dissolves another substance to form a solution.
• An unsaturated solution is one where there is still some undissolved solid present.
• Heterogeneous mixtures have components that are notevenly distributed; the compositionvaries throughout
• Heterogenous mixtures can be a suspension or a colloid.
• A suspension is a heterogeneous mixture in which large particles settle and sedimentation occurs.
• A colloid is a heterogeneous mixture in which very small particles of one substance are distributed evenly throughout another substance.