Chemistry Grade 11 Unit 3: Chemical Bonding and Structure

Chemical Bonding

• The octet rule states that atoms lose, gain, or share electrons to achieve a full outer energy level of eight electrons, resulting in a stable configuration.

Ionic Bonding

• Ionic bonding involves the transfer of electrons from one atom to another, resulting in the formation of ions with opposite charges that attract each other.

Properties of Ionic Compounds

• Ionic compounds are typically hard, brittle, and have high melting points due to the strong electrostatic attractions between oppositely charged ions.
• They are also usually soluble in water and good conductors of electricity when dissolved.

Molecular Shape

• The VSEPR (Valence Shell Electron Pair Repulsion) theory is used to predict the shape of molecules, with the general formula being AXn, where A is the central atom and n is the number of electron domains.

Intermolecular Forces

• Hydrogen bonding is a common intermolecular force that occurs when a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) forms a weak bond with another electronegative atom.

Valence Bond Theory

• Valence Bond Theory explains how atomic orbitals combine to form molecular orbitals, which in turn determine the shape and bonding of molecules.

Covalent Compounds

• The defining characteristic of covalent compounds is that they involve the sharing of one or more pairs of electrons between atoms.
• Covalent compounds are typically soft and flexible, with low melting points, and are often poor conductors of electricity.

Dative Covalent Bonding

• Dative covalent bonding, also known as coordinate covalent bonding, involves the donation of both shared electrons by only one atom.

Resonance

• Resonance occurs when a molecule can be represented by two or more Lewis structures, indicating that the electrons are delocalized and not fixed in a single position.

Covalent Compound Properties

• Covalent compounds are often volatile, meaning they can easily evaporate, and are typically insoluble in water.