Chapter 5 - Bonding

• Bonding

  The way atoms or ions are held together in a substance (electrically by gain or lose)
• Stable bonding

  • Reach the octet / duplet configuration
• Ionic

  • one atom gives, one atom takes
  • formed between a metal and a non-metal
  • results in the transfer of electrons
  • found in compound only
• Positive ions (cations)


  Metals can lose electrons and become positively charged
• Negative ions (anions)


  Non-metals can gain electrons and become negatively charged
• Ionic

  Positive and negative ions held together by strong electrostatic forces of attraction between opposite charges that requires lots of energy to break the bonds
• Covalent Bond

  • sharing of electrons between non-metals
  • found in elements and compounds
  • pairs of shared electron between atoms allowing each atom to gain full outer shell
  • electron shells of each atom overlap and shared electron are shown in area of overlap
• Lone pair

  Pair of valence electrons that are not shared with another atom
• N, O, H exist as diatomic molecules because it requires 2 atoms for the element to reach stable configuration
• Metallic Bond


  • lattice of positive metal ions surrounded by a sea of delocalised electrons
  • atoms held together strongly by metallic bonding in giant metallic structure
  • metal lose electron from outer shell
  • electorn said to be delocalised, move freely between positive metal ions ; result of attraction between positive metal ions and negative delocalised sea electron
  • metal and metal
  • electrostatic attraction
• Properties of metals


  • giant structure of atom
  • arranged in a regular pattern
  • high melting and boiling points
  • conduct heat and electricity (carry electrons)
  • malleable (bent or hammered into shape)
• Alloy


  • harder than pure metals
  • 2 or more different elements
  • different size of atom
  • disrupted regular structure, atoms can no longer slide over each other
• Properties of ionic compounds


  • Usually solid at room temperature
  • high melting and boiling points (volatile)
  • due to strong electrostatic force between positive and negative charged ions because a lot of energy is required to overcome the force, greater charge in ions, stronger force and higher m.p & b.p
  • good conductors in molten state or solution, poor conductors in solid state
  • have mobile ions/free moving ions that can’t conduct in solid state as ions are in fixed position within the lattice and unable to move
• Properties of simple molecular compounds


  • made of molecules that contain just a few atom covalently bonded together
  • low melting and boiling points
  • usually liquids or gases at room temperature
• Ionic compounds have high melting and boiling points due to the strong electrostatic forces between the positive and negative ions
• Giant Covalent Structure (Allotropes)


  • atom of the same element, different structure
  • contains billions of non-metal atoms joined by covalent bond that forms a giant lattice structure
  • high melting and boiling points, large number of atoms held together by strong covalent bonds, to melt need a lot of energy to break the bonds
  • do not conduct electricity (except graphite) because outer shell electron are used to form covalent bonds, no delocalised electron that move through structure to conduct electricity
• Giant covalent structures

  • Diamond, graphite, silicon(IV) oxide
• Balancing Equation


  Number of each atom on the reactant side equals the number of each atom on the product side
• Single covalent bond: A bond between two non-metal atoms in which the electrons are shared equally between the two atoms.
• Double covalent bond: 2 electrons shared between two atoms, strongest type of covalent bond
• Condition for sharing electron

  • 1 share, other must share 1 also
  • once shared both stable
  • stay neutral, non charged
• Properties of simple molecular compounds

  • soluble in water
  • liquid at room temperature
• Properties of simple molecular compounds

  • covalent bond joining the atoms
  • weak intermolecular force between molecules
  • intermolecular forces are very weak compared with covalent bond
  • liquid or gas at room temperature
• Properties of simple molecular compounds

  • the bigger the size of molecules, the higher the m.p & b.p because size of molecules increase, more intermolecular force so m.p & b.p increases also
  • does not conduct electricity (insulator) cuz no free electron or ions that carry charge (sharing electron, no charge, not ions)
• Why does ionic bonds/compounds have high m.p & b.p?

  Due to strong electrostatic force between the positive and negative charged ions that require lots of energy to break the bonds
• Diamond

  • valuable (well cut and polished)
  • tetrahedral arrangement
  • used to make tips of drill and tools cutting edges because of hardness and very high m.p & b.p
  • each carbon covently bonded to 4 carbon atoms that forms a 3D structure with bonds that are difficult to break
• Graphite

  • soft, slippery, fairly unreactive
  • good conductor of electricity
  • use to make dry lubricants, inert electrodes or mixed with clay to make pencil lead
• Soft and Slippery (Graphite)

  • layer of carbon atoms held losely by weak intermolecular forces
  • can slide over each other when force is applied
• Conduct Electricity (Graphite)


  • each carbon atom has one outer electron that is not used to form covalent bonds
  • electron can move freely along the layers from 1 carbon to the next electron said to be delocalised
• High m.p & b.p

  • each carbon atom is covalentbonded to 3 carbons
  • form continuous later of hexagons that is difficult to break
• Silicon (iv) Oxide

  • siliea, found in sand
  • compound made up of elements silicon and oxygen
  • similar structure and properties to diamond
  • used to make glass due to hardness and high m.p & b.p
  • tetrahedral arrangement
• High m.p & b.p (Silicon (iv) Oxide )


  • each silicon atom is bonded to 4 oxygen
  • each oxygen atom is bonded to 2 silicon
  • forms a 3D structure
  • strong covalent bonds are difficult to break