chemistry p1

• The model of atoms change quite a lot over time
• Rutherford


  • Discovered the nucleus and protons
• Chadwick


  • Discovered neutrons
• Bohr


  • Developed our current model of the atom
• The structure of an atom has electrons on the shells around the outside, protons in the middle, and neutrons in the middle
• Protons


  Have a mass of one and a charge of plus one
• Neutrons


  Have a mass of one and a charge of zero
• Electrons


  Have a mass of 1/2000 and a charge of minus one
• Atomic number


  The number of protons and electrons in an atom
• Mass number


  The number of protons plus the number of neutrons
• Isotope

  An atom with the same number of protons but a different number of neutrons
• The mass of an element on the periodic table is the relative abundance of all its isotopes
• Elements are a single type of atom
• Compound

  Two or more elements that are chemically bonded together
• The first attempt at a periodic table was by Newlands in the 1800s
• Mendeleev arranged the periodic table by mass but left gaps, allowing him to predict the properties of undiscovered elements
• Groups

  Go down the periodic table and indicate the number of electrons in the outer shell
• Periods

  Go across the periodic table and indicate the number of electron shells
• Drawing the electronic configuration of an atom

  1. Draw the number of shells based on the period

  2. Fill the shells with the number of electrons based on the group
• Ionic bonding

  The transfer of electrons from a metal to a non-metal
• Ionic charges

  • Group 1 = +1
  • Group 2 = +2
  • Group 6 = -2
  • Group 7 = -1
• Ionic compounds form a giant ionic lattice structure
• Properties of ionic compounds

  • High melting and boiling points
  • Only conduct when molten or dissolved
• Covalent bonding

  The sharing of electrons between two non-metals
• For covalent compounds, the formula can be determined by counting the atoms present
• Properties of simple covalent compounds

  • Low melting and boiling points
  • Generally gases or liquids at room temperature
  • Do not conduct electricity
• Properties of giant covalent compounds

  • High melting and boiling points
  • Do not conduct or dissolve
• Giant covalent compounds

  • Diamond
  • Graphite
• Diamond

  • Made of pure carbon
  • Each carbon makes 4 bonds
  • Incredibly hard
• Graphite

  • Made of pure carbon
  • Each carbon makes 3 bonds
  • Soft and conducts electricity
• Diamond

  • Giant covalent compound
  • Made of pure carbon
  • Each carbon makes four bonds
• Properties of diamond

  • Incredibly hard
  • Rare
  • Beautiful and precious
• Graphite

  • Giant covalent compound
  • Made of pure carbon
  • Each carbon makes three bonds
• Properties of graphite

  • Soft
  • Conducts electricity
• Graphene

  Single sheet of graphite
• Fullerenes

  • Carbon nanotubules or Buckminster fullerenes
  • Made of pure carbon
  • Make three carbon-carbon bonds
  • Incredibly hard
• Uses of fullerenes

  • Lubricant
  • Reinforcement (e.g. in aircraft, bicycles)
  • Drug delivery
• Polymers with cross-links

  • Very fixed in place
  • Burn upon heating
• Polymers without cross-links

  • Can slide across each other
  • Melt upon heating
• Metals

  • Positive atoms in a sea of delocalized electrons
  • Electrons free to move = good conductors of electricity and heat