Chemistry unit review

• Matter


  Anything that has mass and volume
• Mass


  Quantity of matter in an object, measured in kilograms (kg) or grams (g)
• Volume


  How big an object is or how much space it takes up, measured in liters (L), milliliters (mL), or cubic centimeters (cm3)
• States of matter


  • Solid
  • Liquid
  • Gas
• Changing states


  1. SOLID → LIQUID: Melting

  2. LIQUID → GAS: Evaporation (or vaporization)

  3. GAS → LIQUID: Condensation

  4. LIQUID → SOLID: Freezing

  5. SOLID → GAS: Sublimation

  6. GAS → SOLID: Deposition
• Particle theory (PSAM)


  • All matter is made up of tiny particles
  • There are spaces between the particles
  • Particles attract each other
  • Particles are always moving
• Classifying matter

  • Pure substances
  • Mixtures
• Pure substance


  All particles that make up a substance are the same, can be either an element or compound
• Mixture


  Made of two or more different kinds of particles, can be homogenous or heterogenous
• Element


  A substance that cannot be broken down into simpler substances, made up of only one type of atom
• Compound


  Contains two or more elements that are chemically bonded together
• Homogeneous mixture


  A mixture of more than one pure substance that is the same throughout, different parts are not apparent
• Heterogeneous mixture


  A mixture of more than one pure substance not chemically bonded together, different parts are visible
• Examples of mixtures


  • Solutions
  • Colloids
  • Suspensions
• Solution


  Particles are evenly distributed, so you cannot see the individual particles, these particles are the smallest
• Colloid


  The solute particles are smaller than the solvent ones, so they do not separate out, these particles are medium sized
• Suspension

  These appear cloudy, and the particles are not evenly distributed, these particles are the largest and eventually settle out
• Physical properties


  • State (solid, liquid, gas)
  • Color
  • Clarity (transparent, translucent, opaque)
  • Luster (shiny, dull)
  • Hardness
  • Brittleness
  • Form
  • Texture
  • Malleability
  • Ductility (ability to be stretched into a wire)
  • Viscosity
  • Odor
  • Taste
  • Conductivity (ability to conduct electricity or heat)
  • Density
  • Boiling point
  • Solubility (how well it dissolves into water)
• Quantitative data


  Numerical, results from measurements
• Qualitative data


  Non-numerical, qualities
• Chemical properties


  • Color change
  • Release of a gas
  • Formation of a solid
  • Release or absorption of energy
  • The change being difficult to reverse
• Physical change


  Alters only the form or state of a substance, no new substance is created, the chemical composition remains the same, it is usually reversible
• Chemical change


  Changes a substance into a new substance that has different physical & chemical properties & a new chemical formula, it is not usually reversible, the result of chemical reactions
• Indicators of a chemical change

  • Energy (light or heat) is released or absorbed
  • New color change occurs
  • Bubbling indicating gas formation
  • Precipitate (insoluble solid) formation
  • Very difficult to reverse the change
• Atomic Theory is the study of atoms and how they combine to form all types of matter
• Contributors to Atomic Theory

  • Democritus (400 BC)
  • John Dalton (1800s)
  • J.J. Thomson (1897)
  • Ernest Rutherford (1909-1911)
  • Niels Bohr (1912)
  • James Chadwick (1932)
• Dalton's Atomic Theory


  • All matter is made of small, indivisible particles called atoms
  • All the atoms of an element are identical in properties such as size and mass
  • Atoms of different elements have different properties
  • Atoms of different elements can combine in specific ways to form new substances

  
• Thomson's "Plum Pudding" model of the atom

  The atom is considered a positive sphere with negative electrons scattered throughout the atom
• Rutherford's "Gold Foil Experiment"

  The protons and neutrons are condensed within a tiny central nucleus, while the electrons randomly orbit the nucleus

  
• Bohr-Rutherford model of the Atom

  The electrons must be found in specific energy levels, called shells, and each shell could only hold a specific number of electrons, electrons can move around in a shell without losing energy, electrons could jump from one shell to another by gaining or losing energy
• Chadwick's discovery of the neutron

  Tiny particles that had mass but no charge, led to a refinement of the concept of the nucleus and an adjustment to the Bohr-Rutherford model of the atom

  
• All elements are composed of atoms, the atom is the smallest particle that has the properties of that element, the atom is made up of subatomic particles: protons, neutrons and electrons
• Subatomic particles


  • Proton
  • Neutron
  • Electron
• Proton


  Relative mass of 1, electric charge of 1+, located in the nucleus
• Neutron


  Relative mass of 1, no electric charge, located in the nucleus
• Electron


  Relative mass of 0.0005 (negligible), electric charge of 1-, located in energy levels (shells) surrounding the nucleus
• There are 90 elements that occur naturally on Earth and 28 that have been made by chemists
• Classes of elements


  • Metals
  • Non-metals
  • Metalloids
• Metals


  Most elements, most are shiny, silver/gray in color, great conductors of heat and electricity, malleable and ductile, some are reactive while others are not
• Non-metals


  Only 17 elements, do not resemble metals, exist as solids, liquids, or gases at room temperature, some can react really well with metals