The Covalent Bond and Molecular Compounds

Chemistry

Mrs. Coyle

The Periodic Table and Atomic Radius

Types of Bonds

Ionic Metallic Covalent

The Covalent Bond

• The bond in which atoms are held together by their mutual electrical attraction for shared electrons.

Fluorine

Movie Clip

http://www.youtube.com/watch?v=Kj3o0XvhVqQ&NR=1

The Covalent Bond

A single covalent bond is made up of two electrons.

The covalent bond is represented using a straight line.

F — FF F

Molecule

A neutral group of atoms joined together by covalent bonds.

Diatomic Molecules

Molecules made up of two atoms.

There are 7 diatomic molecules.

H2, N2, O2, F2, Cl2, Br2, I2

Hydrogen

H· + ·H H:HHydrogen Hydrogen Hydrogen

Atom Atom molecule

The hydrogen molecule has a single covalent bond.

The electronegativity of each hydrogenatom is the same, so the electrons are shared.

Shared electron pair

Molecular Compounds

Compounds comprised of molecules.

Ionic Compounds Molecular Compounds

Crystal Lattice Molecule

Types of Elements

Metal with non-metal or polyatomic ions

Non-metal with non-metal

Physical State

Solid Solid, liquid or gas

Melting Point High

> 300 CLow

<300 CSolubility in water

Generally high Generally low

Electrical conductivity of solution

Good conductor Poor to none

Molecular Formula

A molecular formula is a chemical formula that is used for molecular compounds.

It shows the types and number of atoms in a molecule.

Note that ionic compounds used the chemical formula called the formula unit.

A molecular formula does not give information about the molecules structure.

Structural Formula

Structural formulas show the arrangement of atoms in a molecule.

In a structural formula, the electron pair is represented by a line

Example: H-H

(single bond: one pair of electrons)

Space Filling Model

Methane

CH4

Ball and Stick Models

Ethane

C2H6

The Water Molecule

•

The Ammonia Molecule

.

NH3