Transcript Covalent Bonding (Molecular Compounds)

Covalent Bonding (Molecular
Compounds)
Subtitle
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