CIE iGCSE Co-ordinated Sciences-C2.7 Metallic bonding- Study Notes- New Syllabus
CIE iGCSE Co-ordinated Sciences-C2.7 Metallic bonding – Study Notes
CIE iGCSE Co-ordinated Sciences-C2.7 Metallic bonding – Study Notes -CIE iGCSE Co-ordinated Sciences – per latest Syllabus.
Key Concepts:
Supplement
- Describe metallic bonding as the electrostatic attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons
- Explain in terms of structure and bonding the properties of metals:
(a) good electrical conductivity
(b) malleability
CIE iGCSE Co-Ordinated Sciences-Concise Summary Notes- All Topics
Metallic Bonding
Metallic bonding is the type of bonding that holds metal atoms together in a giant metallic lattice. In this structure:
- Metal atoms lose their outermost electrons to form positive ions.
- The lost electrons become delocalised and are free to move throughout the lattice, forming a “sea of electrons”.
- The positively charged metal ions are held together by strong electrostatic attractions between them and the delocalised electrons.
This combination of a lattice of positive ions and a sea of delocalised electrons is called a giant metallic lattice, which is responsible for many characteristic properties of metals such as high melting and boiling points, electrical conductivity, and malleability.
Example
Explain the bonding in sodium metal and how the delocalised electrons are involved.
▶️Answer/Explanation
Each sodium atom loses one outer electron to form a positive ion (\( \text{Na}^+ \)). These electrons are delocalised and move freely throughout the lattice. The electrostatic attraction between the \( \text{Na}^+ \) ions and the sea of delocalised electrons holds the metal together:
\( \text{Na} \rightarrow \text{Na}^+ + e^- \)
This metallic bonding gives sodium its characteristic metallic properties.
Example
Describe how metallic bonding occurs in copper metal.
▶️Answer/Explanation
Copper atoms each lose one electron to form \( \text{Cu}^+ \) ions. The delocalised electrons move freely throughout the lattice, creating a strong electrostatic attraction that holds the metal ions together. This structure allows copper to conduct electricity and heat efficiently:
\( \text{Cu} \rightarrow \text{Cu}^+ + e^- \)
Properties of Metals in Terms of Structure and Bonding
The properties of metals can be explained by the presence of a giant metallic lattice with delocalised electrons.
Good Electrical Conductivity
Metals conduct electricity because the delocalised electrons in the metallic lattice are free to move throughout the structure.
- When a potential difference is applied, these electrons flow, allowing an electric current to pass through the metal.
Example
Explain why copper is a good conductor of electricity.
▶️Answer/Explanation
Copper has a metallic lattice in which each \( \text{Cu} \) atom contributes one delocalised electron. These electrons are free to move, allowing copper to conduct electricity efficiently.
Malleability
Metals are malleable because the layers of positive ions in the lattice can slide over each other without breaking the metallic bonds.
- The delocalised electrons continue to hold the ions together even when the metal is reshaped.
Example
Explain why aluminium can be hammered into thin sheets without breaking.
▶️Answer/Explanation
Aluminium has a metallic lattice with delocalised electrons. When layers of aluminium ions are forced to slide over each other, the delocalised electrons continue to hold the lattice together, allowing the metal to be shaped without breaking.