-Types of Covalent Bonds

-Rules for Writing Lewis Dot Structures of Molecular Compounds

Chemistry

Mrs. Coyle

Single Covalent Bond

Fluorine

Single Covalent Bonds in a Structural Formula

The electron pair is shown as a line

F-F

Unshared electrons can be shown as dots.

Double Bond

Two electron pairs are shared

O :: O

O = O

Carbon Dioxide, CO2

O=C=O

Triple Covalent Bond

Three pairs of electrons are shared.

:N:::N:

:N N:

Coordinate Covalent Bond

When one atom contributes a pair of bonding electrons.

·C· + :O: :C::O

The oxygen atom made the contribution.

Polyatomic Ions

A tightly bound group of atoms that behave as a unit and have a charge.

Rules for Writing the Lewis Dot Structure for a Molecule

1. Sum all the valence electrons of each element in the molecule.

2. Draw the skeletal structure of the molecule and put a single bond between each element.

3. If there are more than two elements, you usually put the least electronegative one in the center.

Rules (Cont’d)

4. Draw the electrons in the surrounding atoms, so that each atom will have a complete octet (duet for H).

5. Add the remaining electrons to the central atom.

6. Check that each atom has no more than an octet (duet for H).

7. Check that the total electrons drawn equal the total available valence electrons found in step 1.

Single Covalent Bonds

Write the structural formulas for:

Cl2

NH3

CH4

H2O

Polyatomic Ions

Draw the electron dot structures for:

CO32-

NO3-

SO32-

SO42-