Bonding, Structure and Properties of Matter in GCSE Chemistry

Bonding, Structure and Properties of Matter

Chemical Bonding

There are three main types of strong chemical bonds:

1. Ionic Bonding - Formed between a metal and a non-metal by the complete transfer of electrons, creating positively and negatively charged ions that are held together by electrostatic forces.
2. Covalent Bonding - Formed when atoms share one or more pairs of electrons, creating stable molecules or giant covalent structures like diamond.
3. Metallic Bonding - Found in metals, where the outer electrons are delocalised and free to move, creating a 'sea of electrons' that holds the positive metal ions together.

Structures and Properties

The type of bonding dictates the structure and properties of a substance:

• Simple Molecules - Small, discrete covalent molecules with weak intermolecular forces, resulting in low melting/boiling points and no conductivity.
• Giant Covalent Structures - Extended networks of covalently bonded atoms (e.g. diamond), giving extremely high melting points, hardness, and no conductivity.
• Metallic Structures - Extended lattice of positive metal ions surrounded by a 'sea' of delocalised electrons, allowing high thermal and electrical conductivity.
• Ionic Lattices - Ordered 3D arrangements of oppositely charged ions, held by strong ionic bonds but with weak intermolecular attractions between ions.

States of Matter and Changes

Substances can exist as solids, liquids or gases depending on their bonding, structure and temperature. Changes of state like melting, boiling, freezing and condensing involve breaking and forming intermolecular forces.

Worked Example: Carbon Allotropes

Carbon exhibits different allotropic forms due to its ability to form different types of covalent bonds:

• Diamond - Giant covalent structure, resulting in extreme hardness, high melting point and no conductivity.
• Graphite - Layered covalent structure, with weak intermolecular forces allowing layers to slide, giving lubrication and electrical conductivity.
• Graphene - Single layer of graphite, with unique physical and electrical properties due to its 2D structure.
• Fullerenes - Spherical molecules like buckyballs, with applications in nanotechnology.

Nanoparticles also exhibit unique properties due to their small size and high surface area to volume ratio.

Understanding bonding, structure and resulting properties is crucial in Chemistry, as it underpins the behaviour and applications of different materials.