Nature of covalent and dative covalent bonds

Question 1

What is a covalent bond?

Answer 1

A shared pair of electrons

Question 2

What is covalent bonding?

Answer 2

The electrostatic attraction between a bonding pair of electrons and the nuclei of the 2 atoms involved in the bond.

Question 3

What are the two types of covalent structures?

Answer 3

Molecular and macromolecular

Question 4

What are molecular covalent structures like + their properties + an example of one?

Answer 4

• Atoms are held by strong covalent bonds, but the intermolecular forces between the molecules are weak which means they can be a gas or a liquid.
• Hardness: They are relatively soft since they do not have strong intermolecular forces.
• Melting and boiling points: They have low melting and boiling points due to the weak van der waal’s forces between the molecules.
• Electrical conductivity: They do not conduct electricity since there are no charged particles that are free to move
• Solubility: They dissolve in non-polar solvents because they themselves are not polar. They will not dissolve in water but will dissolve in organic substances.
• example: iodine

Question 5

What are macro-molecular structures like + their properties + an example of one?

Answer 5

• The atoms are held together by strong covalent bonds in a giant network.
• example: diamond and graphite

Question 6

What is diamond and graphite like + their properties?

Answer 6

Diamond:
- each carbon atom bonds to 4 other carbon atoms in a tetrahedral arrangement
- does not conduct electricity, no charged particles
- very hard due to strong covalent bonds

Graphite
- each carbon atom bonds to 3 other carbon atoms, the remaining electron on each atom is delocalised, allowing it to carry a charge through the structure and conduct electricity.
- can be used in pencils and as a lubricant. Although the covalent bonds between the carbon atoms are strong, the van der waal’s forces between the layers are weak, allowing them to slide over each other.

Properties they both have:
- Melting and boiling point: very high since it required large amounts of energy to break the strong covalent bonds.
- Solubility: they are insoluble since it requires large amounts of energy to break the strong covalent bonds

Question 7

What is a dative covalent bond?

Answer 7

A shared pair of electrons with both electrons supplied by one atom.

Question 8

When do dative covalent bonds form?

Answer 8

when a lone pair on one of the atoms is donated to another atom which doesn’t have any electrons available to share.

Question 9

How do you show a dative covalent bond?

Answer 9

With an arrow