LESSON 2

• FORMATION OF A COVALENT BOND - Because nonmetal

  atoms have relatively similar electronegativities, they tend to attract valence electron equally (or almost

  equally) and just share them to achieve a octet (or duet).
• FORMATION OF A COVALENT BOND - Compounds that result from covalent bonding are called molecular compounds.
• TYPES OF COVALENT BOND

  Two nonmetal atoms can form a maximum of three covalent bonds between each other depending on

  the number of electron pairs that they need to share to attain a noble gas configuration.
• TYPES OF COVALENT BOND

  The orbitals that contain each valence electron overlap to form an orbital common to both atoms.
• TYPES OF COVALENT BOND

  SINGLE COVALENT BOND (一)

  DOUBLE COVALENT BOND (=)

  TRIPLE COVALENT BOND (≡)
• FORMAL CHARGE - Covalently bonded atoms do not always share electrons. Some atoms in a molecule or

  polyatomic ion have a higher electronegativity than

  others; thus, attract the shared electrons towards themselves greater than others.
• FORMAL CHARGE - This results in uneven charge distribution within the molecule or ion; that is; some sites are electron-rich, electron–poor, or neutral.
• FORMAL CHARGE - Formal charge compares the number of electrons “owned” by an atom in a molecule or ion with those possessed by the atom in a free state.
• FORMAL CHARGE - The formula for finding the formal charge of an atom in a molecule or ion is given by: formal charge = (no. of valence e ) - no. of −unshared e ) - (no. of shared )
• FORMAL CHARGE


  Formal charges also help determine the correct Lewis

  structure of a molecule or polyatomic ion.
• SHAPES OF MOLECULES


  Molecular Geometry describes the 3 dimensional

  arrangement of atoms within a molecule or polyatomic ion.
• SHAPES OF MOLECULES


  The molecular geometry of molecules or ions that contai only a few atoms can be predicted using the

  molecule’s Lewis structure and the valence shell electron pair repulsion (VSEPR) theory.
• SHAPES OF MOLECULES


  The VSEPR theory suggests that electro pairs around an atom assume an arrangement in space that reduces th repulsions between them.
• SHAPES OF MOLECULES


  This arrangement depends on the number and type of electron pairs (whether bonding or nonbonding).
• SHAPES OF MOLECULES


  The electron domain (ED) geometry is not necessarily the molecular geometry. The molecular geometry only looks at the arrangement of the atoms; the ED geometry considers the effect of the nonbonding

  domains on the shape of the molecule or ion.
• SHAPES OF MOLECULES


  Since electron domains tend to repel each other, the ideal arrangement of atoms in a molecule or polyatomic ion is that minimizes this repulsion. Therefore, a nonbonding domain tends to spread out

  and occupy a larger space than a bonding

  domain. But all domains – bonding and nonbonding – are all attracted to the central atom.
• SHAPES OF MOLECULES - In the valence shell of an atom in a molecule, each electron pair occupies its domain. Each domain is attracted and gets as close as possible to the central atom, but keeps other domains as far

  away as possible.
• SHAPES OF MOLECULES


  Two Electron Domains – separated by 180̊

  Three Electron Domains – separated by 120̊

  Four Electron Domains – separated by 109.5̊