CHEMISTRY (MODULE1)

• Chemistry


  The science that studies the properties, composition and structures of matter and the changes it undergoes
• Properties of Matter

  • Physical Properties
  • Chemical Properties
  • Intrinsic/Intensive Properties
  • Extrinsic/Extensive Properties
• Physical Properties


  Those that a substance shows by itself, without changing or interacting with another substance, e.g. color, melting point, and density
• Chemical Properties


  Those that a substance shows as it changes into or interacts with another substance, e.g. flammability, corrosiveness
• Intrinsic/Intensive Properties


  Independent of the amount of material, e.g. solubility, boiling point, density
• Extrinsic/Extensive Properties


  Dependent on the amount of material, e.g. mass, weight, volume
• Changes in Matter

  • Physical change
  • Chemical Change
• Physical change


  Occurs when a substance alters its physical form, NOT its composition (melting, sublimation, evaporation, condensation, freezing, deposition)
• Chemical Change


  Occurs when a substance is converted into a different substance (chemical reactions such as burning and oxidation)
• States of Matter

  • Solid
  • Liquid
  • Gas
• Solid


  Has a fixed shape with particles close together and organized
• Liquid


  Conforms to the container's shape but fills the container only to the extent of the liquid's volume with particles which are close together but disorganized
• Gas


  Conforms to container shape but fills the entire container and with particles far apart and disorganized
• Substances

  • Elements
  • Compounds
• Elements


  Substances made up of only one kind of atom
• Types of Elements

  • Metals (electric conductors)
  • Nonmetals (non-conductors)
  • Metalloids (semi-conductors)
• Compounds


  Substances made up of two or more kinds of atoms; cannot be separated by physical means
• Types of Compounds

  • Acids (turn litmus paper from blue to red)
  • Salts or Neutral compounds
  • Bases (turn litmus paper from red to blue)
• Mixtures


  • Heterogeneous
  • Homogenous
• Heterogeneous


  Mixture of substances of different phases
• Homogenous


  Composition is the same throughout
• Types of Homogenous Mixtures

  • Colloids
  • Suspensions
• Colloids


  Composed of two phases of matter (dispersed and continuous phase)
• Suspensions


  Mixture of liquid and relatively large particles of solids
• Increasing atomic radius

  Increasing metallic property
• Increasing ionization potential, electron affinity, electronegativity

  Increasing non-metallic character
• Law of Definite Composition: a compound is formed by combining elements in ratios of simple whole numbers
• Law of Definite Proportion: every sample of a specific substance always contains the same proportion by mass of its components
• Law of Multiple Proportions: if two elements form multiple compounds, the ratios of the masses of the second element combining with a fixed mass of the first elements will be in ratios of small whole numbers
• Ions


  Atoms or groups of atoms that carry an electric charge
• Cations

  Carry positive charges
• Anions


  Carry negative charges
• Electrically neutral


  If the number of protons (or atomic number) is equal to its number of electrons
• Electrically positive


  If the number of electrons is less than its number of protons
• Electrically negative


  If the number of electrons is greater than its number of protons
• Electrical charge depends on the loss/gain of electrons, not of protons
• Mole


  Amount of substance that contains as many entities (atoms, molecules or other particles as 12 grams of pure carbon-12 atoms
• 1 mole = 6.0221415 x 10^23 atoms ~ 6.022 x 10^23 atoms (Avogadro's number)
• 1 mole of atoms of a pure element in grams (g) = the atomic weight of the element in atomic mass units (amu's)
• Stoichiometry


  Determination or measurement of chemical quantities; often involves conversion processes