Chemistry

• 5 clues that tell us a chemical change has taken place

  • Change of color, change in shape (possibly)
  • Change of temperature
  • Smell
  • Gas formation
  • Creation of a precipitate
• Particle Theory of Matter


  Describes the structures of matter and their behavior
• Particles in matter


  • All matter is made up of very tiny objects called particles
  • All particles have spaces between them
  • Particles present in matter are always moving
  • The particles in a substance attract one another
• Physical property


  Describes something that can be observed or measured
• Chemical property


  Describes the ability of a substance to change into a new substance(s)
• Physical change


  A change in properties such as texture, shape, or state
• Chemical change


  A change that causes a new substance to be formed
• Molecule


  Forms when atoms share electrons to form small groups
• Molecular compound


  Formed when non-metals combine
• Heterogeneous mixture


  When the different parts are visible
• Heterogeneous mixture


  • Chocolate chip cookie
• Homogeneous mixture


  When all parts are not visible because they are dissolved and look the same
• Homogeneous mixture


  • Tea
• Mechanical mixture


  The parts that make it up are all visible and can be taken apart. It is a heterogeneous mixture
• Suspension mixture


  Cloudy mixture. Parts can be separated with filter paper. Heterogeneous mixture
• Suspension mixture


  • Salad dressing
• Solution mixture


  Parts that make up it are not visible because they get dissolved. Homogeneous mixture
• Solution mixture


  • Tea
• Pure substance


  Made up of only one kind of matter and is either an element or compound
• Element


  Substance that cannot be broken down into anything simpler
• Compound


  A pure substance that is made from two or more elements
• You get periodic table
• Subatomic particles


  • Electrons
  • Protons
  • Neutrons
• Atomic theory


  The study of atoms
• Nucleus


  The middle part located in the atom
• Electrons


  Negatively charged particles in atoms located on the rings of the atom
• Neutrons


  Neutral particles and are located in the nucleus of the atom
• Protons


  Positively charged particles also located in the nucleus of the atom
• Atomic number


  Number of protons and electrons
• Atomic mass


  Atomic number + neutrons
• Row numbers on periodic table

  Number of rings needed
• Ion


  An atom that has a charge
• Formation of ions


  Ions form when an atom gains or loses an electron and this causes a charge which can be negative or positive
• Ionic compound


  Pure substances consisting of metals or non-metals. High melting points, form crystals, dissolve in water to form solutions that conduct electricity
• Ionic bond


  Result from the attraction between oppositely charged ions (opposites attract so + and -)
• Positive charge


  Occurs when an atom loses an electron
• Negative charge


  Occurs when an atom gains an electron
• Covalent bond


  When two atoms are bonded together by sharing electrons
• Non-polar covalent bond


  Electrons are shared equally
• Polar covalent bond


  Electrons are shared unequally