different compounds that have the same molecular formula but differ in their connectivity (in the sequence in which their atoms are bonded together)

1. Carbon is tetravalent - they have 4 valence electrons and can form four bonds

2. A Carbon atom can use one or more of its valence electrons to form single, double, or triple bonds to other Carbon atoms 

Electronegativity

and the

Periodic Table

Increases from left to right

Increases from top to bottom

Step 1: Determine the total number of valence electrons.

Step 2: Write the skeleton structure of the molecule.

Step 3: Use two valence electrons to form each bond in the skeleton structure.

Step 4: Try to satisfy the octets of the atoms by distributing the remaining valence electrons as nonbonding electrons.

Section 1.5

Rules for Resonance

1. They exist only on paper

2. Only allowed to move electrons

3. All of the structures must be proper Lewis structures

4. The energy of the actual molecule is lower than the energy that might be estimated for any contributing structure

5. Equivalent resonance structures make equal contributions to the hybrid, and a system described by them has a large resonance stabilization

6. The more stable a structure is (when taken by itself), the greater is its contribution to the hybrid

    a) The more covalent bonds a structure has, the

        more stable it is

    b) Structures in which all of the atoms have a

        complete valence shell of electrons are especially

        stable and make large contributions to the hybrid