Covalent Bonds

Review

• Reactivity– Electron configuration – Stability

• Chemical bond• Lewis dot symbol

Covalent bond

• Bond in which two valence electrons are shared by two atoms– Occurs with elements close to each other on the

periodic table– Ex: H2O, NH3 (ammonia), CH4 (methane)

– Between a nonmetal and a nonmetal

3 Types of Covalent Bonds

• Single Covalent Bond• Double Covalent Bond• Triple Covalent Bond

3 Pencil Demo for Single, Double and Triple Covent bonds

• Make as many observations as you cani.e. facial expressions, body position, muscles

used, noises made, force or energy exerted, etc.

Single Covalent Bonds

• Each atom shares one pair of electrons• Each atom shares 2 electrons• Longest bond• Weakest bond of the three

H—H

Lewis Structur

e

Double Covalent Bonds

• In a double bond, each atom shares two pairs of electrons

• Each atom shares 4 electrons• Medium length bond• Medium strength bond

Lewis Structur

e

O2

Triple Covalent Bond

• In a triple covalent bond, each atom shares three pairs of electrons

• Each atom shares 6 electrons• The shortest bond• The strongest bond• Carbon, nitrogen, oxygen, and sulfur can form

double and triple covalent bonds

N2

Lewis Structur

e

Strength of Covalent Bond

• Several factors control bond strength—Number of shared electrons-the more

electrons shared, greater the bond—Size of the atom—Bond length – the greater the bond length,

the weaker the bond

SubstanceMolecule• Two or more atoms

chemically bonded together

Compound• Two or more elements

chemically bonded together

MoleculesDiatomic

CO

HCl

Memeorize Diatomic Elements

– elements that exist as two

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

– HONClBrIF– Magnificent 7-don’t forget H

MoleculesPolyatomic

O3

H2ONH3

CO2

CompoundMolecular Compound

HCl CO

H2ONH3

CO2

Binary Molecular Compound

Covalent Molecule Properties

• Covalent molecular solids tend to be soft solids, liquids, or gases at room temperature

• Low melting and boiling points• Poor conductors of heat and electricity• Non-electrolytes – do not conduct electricity

in water