Chemical Bonds are attractive forces between atoms in compounds.

Ionic bonds involved the transfer of electrons from atom to atom.

Covalent bonds involve the sharing of electrons.

Electrons available for use in bonding are called valence electrons. Among the representative elements the valence electrons are in the highest occupied energy shell.

Electron-dot-structure of atoms & ions

Octet rule

Ionic bond

Electron configuration of ions

Isoelectronic species
 
 

Ionic solids are mostly comprised of positive and negative ions arranged in orderly crystalline patterns. Discrete molecules do not exist.

Monatomic          vs          polyatomic ions
  Al³⁺, S^2-                                   (NH₄)⁺, (PO₃)^3-

Covalent Compounds

      H : H    nonpolar covalent single bond

    : N ::: N:   nonpolar covalent  triple bond

      H : Cl:     polar covalent   single bond

Some atoms can complete their octet in more than one way.

H H

H C H H C O

H

O C O H CN

Coordinate covalent bond

H ⁺

H N H ammonium ion

H

Bond length and energy

C-C   vs   C=C    vs CC

Resonance

:O-S=O: <---> :O=S-O:

A system for Writing Electron Dot Structures

X = valance electrons available

Y = total valance electrons needed to give each atom an octet.

Y - X = electrons to be shared.

Molecular Geometry - VSEPR

linear; H-CN; O=C=O

bent; O-S=O; H-S-H

trigonal planer         H
                               |
                          H C=O

trigonal pyramidal  NH₃
H : N : H
     H

tetrahedral    CH₄

Electronegativity - The relative ability of an atom to attract shared electrons.

Partial Charge

Polar bonds vs Polar Molecules