Covalent Bonding (Molecular Compounds)

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Properties of a Covalent Bond

• Formed when at least one pair of electrons are shared between non-metals

• Can be equal sharing (50-50) and if so is called non-polar

• Or unequal sharing (based on electronegativity difference) and is called polar

• All elements involved still obey the octet or duet rule when the compound is formed

Properties of Covalent Compounds

• Weak bonds

• Soft solids, or liquids, or gases at room temperature

• Low melting points, and low boiling points

• Share electrons not exchanging

• Polar Covalent will dissolve in water

• Non-Polar covalent will not dissolve in water

• Do not conduct electricity

Continuing Properties

• Each element the in compound have 8 valence electrons when completed

• Non-polar covalent substances will dissolve in non-polar covalent liquids

Types of Covalent Compounds (Molecular)Single Covalent Bonds

• Formed by the sharing of one pair (2 total) of electrons

• Most common type of covalent bond

• Weakest type of covalent compound

Types Continued (Double Covalent Bonds)

• Formed by the sharing of 2 pairs (4 total) of electrons

• Stronger than a single bond, better at distributing energy and much harder to break apart

Types Continued: Triple Covalent Bond

• Formed by the sharing of 3 pairs of electrons (6 total)

• Strongest type of covalent bond that exists

• Provides stability and is very hard to break apart

Bond Polarity

• Only applies to Covalent Compounds (molecular) and never to an ionic compound

• Polarity tells us which part of our molecule has a slight negative charge, and which part has a slight positive charge

• Polarity is based on electronegativity difference between the elements

• Elements that have higher electronegativity values will become the negative end of the molecule

• Elements with the lower electronegativity will become the positive end of the molecule

Non-Polar Covalent Bond

Formed between 2 elements when the electronegativity difference is 0.0-0.4

All diatomics are non-polar in terms of bonding

To be non-polar means that no element is strong enough to share in a way that makes the bond uneven from a distribution of charge standpoint

Polar Covalent Bond

• Bond that is formed when the electronegativity difference between the elements is between 0.4 and 1.7

• Still a covalent bond but the sharing of the electrons is unequal

• More electronegative element will have the shared electron pair more often in its area than the element with the lower electronegativity

• The more electronegative element will take on a slight negative charge

• The less electronegative element will take on a slight positive charge