Physical Sciences Grade 11: Electrostatic Forces

Here are the study notes:

Chemical Bonding

• Chemical bonds are formed when atoms approach each other and the electrostatic forces of attraction and repulsion are balanced
• A chemical bond exists when the attractive and repulsive forces are balanced
• The "rule of two" states that a chemical bond involves the formation of electron pairs, known as a bonding pair

Bond Formation and Stability

• As atoms approach each other, the potential energy within the system decreases
• At a critical point, the potential energy will be at its lowest when the electrostatic attractive and repulsive forces are balanced
• This is when the combination is at its most stable
• The distance between the nuclei of each atom is now fixed, known as the bond length

Bonding

• He atoms do not bond because they have a full valence shell and cannot undergo bond formation
• Lewis diagrams can show combinations of different atoms
• A lone pair is a pair of electrons that are not involved in chemical bonding
• A bonding pair is a pair of electrons that are formed when a chemical bond is formed
• Lone pairs do not make chemical bonds
• The dative covalent bond is a special covalent bond formed from a lone pair

Multiple Bonding

• More than one bonding pair can be formed between the same atoms
• This leads to the formation of double and triple bonds
• Examples: O₂ (double bond), N₂ (triple bond), and HCN (triple bond)

Dative Covalent Bond

• The dative covalent bond must be shown using NH₃⁺ and H₂O as examples
• An atom with an empty valence shell is able to share a lone pair from another atom
• The atom with the empty valence shell is usually a hydrogen atom
• NH₃ and H₂O have lone pairs and are able to "share" a lone pair

Intermolecular Forces

• Intermolecular forces are the forces of attraction and repulsion between atoms or ions within a chemical bond
• There are three types of chemical bonds: covalent, ionic, and metallic

Atomic Combinations - Molecular Structure

• Chemical bonds within a chemical substance play a significant role in chemical and physical properties
• There are different types of chemical bonds: covalent, ionic, and metallic
• Covalent bonds occur between non-metal atoms through electron sharing
• Ionic bonds occur between a metal atom and a non-metal atom through electron transfer
• Metallic bonds occur between metal atoms through electrostatic forces of attraction

Molecular Shapes

• Molecules exist in three-dimensional space with different shapes depending on the arrangement of the atoms and number of bonds
• This is explained through VSEPR theory
• Repulsive forces exist between electron pairs that are present in the valence shells after bonding
• These repulsive forces cause stress within the molecule, making electron pairs repel each other as far away as possible to minimize the stresses
• Molecules wish to be in the lowest, most stable energy state

Ideal Shapes

• Ideal shapes are based on a central atom with no lone pairs surrounding them
• There are five ideal shapes: linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral

Non-Ideal Shapes

• Non-ideal shapes have lone pairs of electrons on the central atoms
• Examples: angular (H₂O) and pyramidal (NH₃)

I hope these notes help! Let me know if you have any questions.