science chem

• Matter


  Anything that takes up space and has mass
• Mass


  A measure of the number of particles in an object
• Weight


  The influence of gravity on mass
• The density for any variety of matter can be calculated using the equation: D = m/V
• Units typically used to calculate density are grams (for mass) and milliliters (mL for volume)
• Cubic centimeters (cm³) is equivalent to milliliters
• A substance can be defined as any variety of matter with identical properties and composition
• Types of substances

  • Elements
  • Compounds
• Elements


  Cannot be broken down chemically; made up of a particular atom
• Compounds


  Can be broken down chemically; formed from the bonding of two or more elements
• Mixtures are the results of the combination of elements and/or compounds
• Homogeneous mixtures


  Have only one phase and a uniform appearance throughout
• Heterogeneous mixtures


  Made up of more than one phase and can be separated physically
• Physical properties

  Observable and measurable properties of substances
• Chemical properties


  Properties observed when a substance reacts with other substances
• Energy is defined as the ability to do work
• Energy is conserved; it is not created or destroyed
• Potential energy


  Stored energy
• Kinetic energy

  Moving energy
• Forms of energy

  • Potential energy
  • Kinetic energy
  • Chemical energy
  • Nuclear energy
  • Radiant energy
  • Thermal energy
  • Electrical energy
  • Sound energy
  • Mechanical energy
• Exothermic reaction


  More energy is released than absorbed
• Endothermic reaction


  More energy is absorbed than released
• Activation energy (Ea)


  The energy required to start a reaction
• Heat of reaction


  The change in energy of the reactants or products
• Phases of matter

  • Solid
  • Liquid
  • Gas
  • Plasma
• Gases


  Have no definite volume and can be compressed<|>Have no definite shape and take the shape of their container<|>Gas molecules are spread far apart
• Energy of the reactants or products is called the heat of reaction
• Heat of reaction


  Change in heat energy or enthalpy
• Phases of matter

  • Solid
  • Liquid
  • Gas
  • Plasma
• Cold is defined as T<0°C
• Warm is defined as 0<T<100°C
• Hot is defined as T>100°C
• Hotter is defined as T>100,000°C
• Basic properties of gases

  • Gases have no definite volume and can be compressed
  • Gases have no definite shape and take the shape of their container
  • Gas molecules are spread far apart
• Kinetic Molecular Theory (KMT)


  Gas molecules are individual particles that travel in a straight-line random motion until they collide or are acted upon by another force<|>Gas molecules continuously collide and transfer energy during these collisions<|>The volume of individual gas molecules is negligible compared to the volume they occupy<|>No forces of attraction are considered to exist between the gas molecules
• Gases exert a pressure on other objects as they collide
• Pressure


  The amount of force exerted on an area
• Standard pressure is defined as 1.0 atmospheres (atm)
• Units of pressure corresponding to 760 mm Hg

  • 1.0 atmospheres (atm)
  • 760 torr
  • 101.3 kilopascals (kPa)
  • pounds per square inch (psi)
• Boyle's Law


  At a constant temperature, there is an inverse relationship between pressure and volume