chemistry covalent bonding

• Covalent bonds are formed by the sharing of electrons between atoms.
• Structure and bonding of diamond and graphite

  • Explaining their properties such as heat and electrical conductivity, hardness, and suitability for diverse applications
• Polar and non-polar character of molecules

  • Referenced to the shape of the molecule
• Hydrogen can achieve a noble gas configuration through covalent bonding by sharing its one outer shell electron
• Atoms form covalent bonds by sharing electrons to fulfill the octet rule
• Hydrogen cannot meet the octet rule due to having one electron in its outer shell
• Hydrogen is a special case in covalent bonding
• Bond pairs vs. Lone pairs

  Bond pairs are shared electrons involved in bonding, while lone pairs are non-bonding electrons
• Physical properties of molecular substances

  • Including melting points, boiling points, and non-conduction of electricity with reference to their structure
• Shapes of molecules

  • Linear, bent, pyramidal, and tetrahedral shapes determined by valence shell electron pair repulsion (VSEPR) theory
• Strength of a covalent bond

  Measured by bond enthalpy, represented by H, and measured in kJ
• Relative strengths of intramolecular bonding and intermolecular forces

  • Including covalent bonding, dispersion forces, dipole-dipole interactions, and hydrogen bonding
• Representing molecules

  • Use of Lewis (electron dot) structures, structural formulas, and molecular formulas to model various molecules such as hydrogen, oxygen, chlorine, nitrogen, hydrogen chloride, carbon dioxide, water, ammonia, methane, ethane, and ethene
• Covalent bonding

  Sharing of outer shell electrons, not all outer shell electrons have to be involved, generally with non-metals, formed by electrostatic attraction
• Electron shell diagram vs. Electron dot diagram

  Shell diagram shows all electron shells and their electrons, while dot diagram shows only valence electrons as dots around the chemical symbol
• Chlorine (Cl) has 7 valence electrons and can form covalent bonds to meet the octet rule
• Octet rule


  Atoms prefer to have eight electrons in their valence shell or achieve a noble gas configuration
• Molecular formula


  • Counts the number of each sort of atom present
• Physical or spatial representations provide 3-D views of molecules to aid in understanding properties better
• Electron dot diagram


  • Atom with most bonding electrons placed near the centre, valence electrons arranged around to try and have eight electrons (or two for hydrogen) sharing
• Structural formula

  • Each pair of electrons shown, lone pairs not shown. Structure is drawn in 2-D (flat)
• Molecular formula tells you nothing (or very little) about the way the atoms are joined
• Exceptions to octet rule exist where molecules do not follow the octet rule. Some have fewer than eight electrons, many have more than eight. An example is sulfuric acid H2SO4 with 12 shared electrons
• There are advantages and limitations to all the models presented
• Physical or spatial representations

  • SPACE FILLING
  • BALL AND STICK MODELS
• Electron dot diagram

  • WATER
  • METHANE
• Valence structure

  • Each pair of electrons, whether bonding or not, is represented by a single line. Structure is drawn in 2-D (flat)
• Molecular formula

  • CO2
  • CH4
  • NH3
  • H2O
  • C6H12O6
• Chlorine covalent bonding


  If two chlorine atoms come together, they can share their electrons and form a covalent bond where they have eight electrons in their outer shells
• Oxygen (O)


  Atomic number 8, 6 valence electrons
• Chlorine (Cl)

  Atomic number 17, 7 valence electrons
• Oxygen covalent bonding


  If two oxygen atoms come together, they can share their electrons and form two covalent bonds where they have eight electrons in their outer shells
• Covalent molecular element

  Made of atoms of the same element held together by covalent bonding
• Nitrogen (N)


  Atomic number 7, 5 valence electrons
• Nitrogen covalent bonding

  If two nitrogen atoms come together, they can share their electrons and form two covalent bonds where they have eight electrons in their outer shells
• Covalent bonding

  The electrostatic attraction between positive nuclei and shared pairs of electrons
• One bond is formed in a chlorine molecule covalent bond - single bond
• Chlorine octet rule


  It must have one extra electron in its outer shell to meet the octet rule
• Oxygen octet rule

  It must have two extra electrons in its outer shell to meet the octet rule
• Two bonds are formed in an oxygen molecule covalent bond - double bond