Chemistry chapter 2

• Matter


  Anything that has mass and occupies space
• Classification of matter


  • Element
  • Compound
• Element


  A substance that contains only one type of atom
• Compound


  A substance that consists of two or more elements chemically bonded together
• Particles


  • Ions
  • Atoms
  • Molecules
• Ion


  Charged particles which are positively charged or negatively charged
• Atom


  The smallest particle in an element
• Molecule


  A group of atoms that are chemically bonded together
• Molecular element


  A molecule that consists of one type of atom only
• Molecular compound


  A molecule that consists of two or more different types of atoms
• States of matter


  • Solid
  • Liquid
  • Gas
• Solid


  • Particles can only vibrate and rotate about their fixed positions
  • Have very strong attractive forces between particles
• Liquid


  • Particles can vibrate, rotate and move throughout the liquid
  • Particles are bonded by strong attractive forces but weaker than those in a solid
• Gas


  • Particles can vibrate, rotate and move freely
  • Have very weak attractive forces between particles
• Kinetic particle theory


  Used to describe the three states of matter
• Changes in states of matter

  • Evaporation
  • Melting
  • Boiling
  • Freezing
  • Condensation
  • Sublimation
• Evaporation


  Vaporization of liquid that occurs on the surface at all temperatures between the melting point and boiling point
• Melting


  Solid changes to liquid when particles gain kinetic energy and vibrate more rapidly, overcoming attractive forces
• Boiling


  Liquid changes to gas when particles gain kinetic energy and move more rapidly, overcoming attractive forces
• Freezing


  Liquid changes to solid when particles lose kinetic energy and form attractive forces in fixed positions
• Condensation


  Gas changes to liquid when particles lose kinetic energy and form attractive forces to bond more closely together
• Sublimation


  Solid changes directly to gas when particles gain kinetic energy and vibrate more rapidly, overcoming attractive forces
• Greek philosopher Democritus introduced the idea of atom


  Around 450 BC
• Historical development of the atomic model

  • John Dalton's atomic model
  • J.J. Thompson's atomic model
  • Ernest Rutherford's atomic model
  • Niels Bohr's atomic model
  • James Chadwick's atomic model
• John Dalton's atomic model


  Atom is the smallest particle in an element, all atoms of an element are the same, different elements have different atoms, atom cannot be divided, created nor destroyed
• J.J. Thompson's atomic model

  Atom is a positively charged sphere with electrons embedded in it
• Ernest Rutherford's atomic model

  Center of the atom contains positive charge concentrated in a very small region called nucleus, most of the space around the nucleus is empty, electrons move randomly around the nucleus
• Niels Bohr's atomic model

  Electrons orbit the nucleus in fixed shells
• James Chadwick's atomic model

  Nucleus is made up of protons and neutrons, electrons orbit the nucleus in fixed shells
• Subatomic particles


  • Proton
  • Neutron
  • Electron
• Proton


  Positive charge, has mass
• Neutron


  Neutral charge, has mass
• Electron


  Negative charge, very small mass