04- Chemical bonding

• atoms combine to achieve the electronic configuration of noble gases, full valence shell of electrons

  valence shells undergo changes to fill their valence shell and become stable

  • loss of electrons
  • gain of electrons
  • sharing of electrons
• positive ions (cations) have a net positive charge and usually have a noble gas electronic configuration through losing electrons

  negative ions (anions) have a net negative charge and usually have a noble gas electronic configuration through gaining electrons
• Ionic bonding

  • ionic bond: mutual electrostatic attraction between ions of opposite charges
  • mostly between metals and non-metals

  Ionic compounds

  • ionic compound: neutral substance that consists of ions of opposite charges held together by ionic bonds
  • positive (metal) and negative (non-metals)

  Ionic structures

  • giant ionic crystal lattice: 3 dimensional structure of alternating positive and negative ions
• The covalent bond

  • covalent bonding: sharing of electrons between atoms to achieve the noble gas configuration (bonding pair)
  • occurs between non-metals/ metalloid and non-metal
  • single covalent bond: 1 pair of electrons shared
  • double covalent bond: 2 pair of electrons shared

  Covalent molecules

  • mostly simple covalent molecules, countable number of atoms (H2O)
  • giant covalent molecules, uncountable number of atoms (diamond, graphite and silicon dioxide)
  • macromolecules

  As the Mr increases, the strength of intermolecular forces increases
• Metallic bonding

  • metal atoms are held together by metallic bonding
  • metallic bond: mutual electrostatic attraction between positively charges ions in a metal and the "sea of mobile/delocalised electrons"
  • giant metallic lattice structure held together by positive ions in a "sea of delocalised electrons"
• • valency: the number of electrons that must be lost, gained or shared in order for the atom to attain a noble gas configuration