CLASSIFICATION OF MATTER

1. PURE SUBSTANCES - defined as substances that are made of only one type of atom or molecule. The purity of a substance is the measure of the extent to which a given substance is pure.
  • Pure substance exhibit very well-defined physical properties, or properties that are not connected with the substance’s ability to combine with different substances.
KINDS OF PURE SUBSTANCES
  • ==ELEMENTS== - a species of atoms having the same number of protons in their atomic nuclei (that’s, the same atomic number, or Z). 118 elements have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. They’re classified into “metal’, “non-metal”, and “metalloids”.

@@TRIVIA@@ - the noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a group of chemical elements with similar properties; under standard conditions, they’re all odorless, colorless, monoatomic gases with very low chemical reactivity. Noble gases have very low boiling and melting points, which makes them useful as cryogenic refrigerants.

  • ==COMPOUNDS== - a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.

4 TYPES OF COMPOUNDS, DEPENDING ON HOW THE CONSTITUENT ARE HELD TOGETHER:

  • Molecules held together by covalent bonds
  • Ionic compounds held together by ionic bonds
  • Intermetallic compounds held together by metallic bonds
  • Certain complexes are held together by coordinated covalent bonds.
2. MIXTURES - a material made up of 2 or more different substances which are mixed.
  • Mixtures are one product of mechanically blending or mixing chemical substances such as elements and compounds, without chemical bonding or chemical change so that each ingredient substance retains its own chemical properties and makeup.
  • Some mixtures can be separated into their components by using physical (mechanical/thermal) means.
KINDS OF MIXTURES
  1. ==HOMOGENEOUS MIXTURE== - a solid, liquid, or gas mixture that has the same proportions of its components throughout any given sample.
  • Homogeneous mixtures have the same composition throughout and the individual parts of the mixture are not easily identifiable.
  • Homogeneous mixtures are also referred to as solutions.
  • E.g. vinegar, perfume/cologne, honey, Jell-O, mouthwash, vegetable oil, coffee, water, blood.
  1. ==HETEROGENOUS MIXTURE== - a mixture having a non-uniform composition. The composition varies from 1 region to another, with at least 2 phases that remain separate from each other, with clearly identifiable properties.
  • E.g. Lucky charms, captain, granite/marble, chocolate chip cookies, sand in water, and (suspensions).
TYPES OF HETEROGENEOUS MIXTURE
  1. @@SUSPENSION@@ - contains solid particles sufficiently large for sedimentation. The particles may be visible to the naked eye, and usually must be larger than 1 mm., and will eventually settle.
  2. @@COLLOIDS@@ - a mixture in which 1 substance of microscopically dispersed insoluble particles is suspended throughout another substance.
    • Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color.