# Metallic Bonding

> Edexcel International GCSE Chemistry · 4CH1 2017
> Source: https://www.owlsprep.com/study/edexcel-igcse-chemistry-s1-metallic-bonding/

This guide covers the 2D metallic lattice structure, electrostatic bonding model, and explanations for core metal properties (conductivity, malleability) required for Edexcel IGCSE Chemistry Paper 2C Higher tier.

**Prerequisites:** [Knowledge of ionic and covalent bonding models](https://www.owlsprep.com/study/edexcel-igcse-chemistry-s1-ionic-covalent-bonding/); [Understanding of electrostatic attraction between charged particles](https://www.owlsprep.com/study/edexcel-igcse-chemistry-s1-structure-of-atoms/)

## Learning objectives

- Draw and label a 2D metallic lattice diagram showing positive ions and delocalised electrons
- Explain metallic bonding as electrostatic attraction between a positive metal ion lattice and delocalised electrons
- Link metallic structure to electrical conductivity and malleability for exam response questions

## 2D Metallic Lattice Diagrams

Metals have a giant regular lattice structure that you will be required to represent in 2D for exam answers. The lattice is made of positively charged metal ions arranged in uniform, repeating rows and columns, surrounded by negatively charged delocalised electrons.

**Metallic lattice** — A regular 2D or 3D arrangement of positively charged metal ions, surrounded by a freely moving sea of delocalised electrons.

**Worked example:** Draw and label a 2D diagram to represent the structure of a metallic lattice, as required for Edexcel IGCSE Chemistry exam answers.

1. 1. Draw 3–4 evenly spaced, uniform rows of circles, each representing a positive metal ion. Label each circle with a positive charge, e.g. $M^+$ (replace $M$ with the relevant metal symbol if given in the question).
2. 2. Add small dots or negative signs scattered evenly between the circles to represent delocalised electrons.
3. 3. Add an explicit label pointing to the scattered negative charges: 'delocalised electrons (sea of electrons)'.
4. 4. Ensure the ion arrangement is regular, not random, to clearly show the lattice structure.

> **tip**
>
> You do not need to draw more than 4 rows of ions for full marks. Unlabelled dots for electrons will not score marks, so always add the explicit delocalised electrons label.

## The Metallic Bonding Model

Metallic bonding is the strong force that holds the giant metallic lattice together. Like ionic bonding, it relies on electrostatic attraction between oppositely charged particles, but has a unique arrangement of charges.

**Metallic bonding** — The strong electrostatic attraction between the regular lattice of positive metal ions and the negatively charged sea of delocalised electrons surrounding the ions.

**Worked example:** State and explain the type of bonding present in a sample of pure lithium metal.

1. 1. Identify the bonding type: Pure lithium, a group 1 metal, has metallic bonding.
2. 2. Describe the lattice structure: Lithium forms a regular lattice of positive lithium ions ($Li^+$).
3. 3. Identify the delocalised particles: Each lithium atom loses its single outer shell electron, forming a sea of delocalised negatively charged electrons surrounding the ion lattice.
4. 4. Explain the bonding force: Strong electrostatic attraction between the positive $Li^+$ ions and negative delocalised electrons holds the lattice together.

> **warning**
>
> Never describe metallic bonding as 'attraction between positive and negative ions' — this is the definition of ionic bonding, and will get zero marks. Always explicitly reference the sea of delocalised electrons.

## Explaining Physical Properties of Metals

The structure of the metallic lattice directly explains the two core physical properties you are required to recall: electrical conductivity and malleability. Examiners frequently ask you to link structure to property, so exact terminology is critical for full marks.

**Worked example:** Explain why copper metal is used for electrical wiring, with reference to its structure and bonding.

1. 1. Identify the relevant property: Copper is an excellent conductor of electricity.
2. 2. Link to structure: Copper has a metallic lattice with a sea of delocalised electrons.
3. 3. Explain the mechanism: When a potential difference is applied, the delocalised electrons are free to move through the lattice, carrying electrical charge from one end of the metal to the other.

**Worked example:** Explain why iron metal can be hammered into gates without shattering.

1. 1. Identify the relevant property: Iron is malleable.
2. 2. Link to lattice structure: The positive iron ions in the metallic lattice are arranged in uniform, flat layers.
3. 3. Explain the mechanism: When force is applied, the layers of positive ions can slide over one another. The sea of delocalised electrons moves with the ions, so the electrostatic attraction holding the lattice together is not broken, and the metal changes shape rather than shattering.

**Exam command terms**

- **Explain the property** — You must link the metallic lattice structure (ions / delocalised electrons) to the property, not just state the property. *(If asked 'Explain why metals are malleable', you must mention sliding layers of ions, not just say 'they can be hammered into shape'.)*

## Common pitfalls

- **Wrong:** Drawing a random arrangement of ions in the metallic lattice diagram.
  - Why it fails: The lattice is a regular repeating structure, so random arrangements do not match the required model, leading to lost marks.
  - Correct: Draw uniform, evenly spaced rows of positive ions to clearly show the regular lattice structure.
- **Wrong:** Describing metallic bonding as attraction between positive and negative ions.
  - Why it fails: This is the definition of ionic bonding, not metallic, so examiners will award zero marks for this description.
  - Correct: Explicitly state that metallic bonding is electrostatic attraction between positive metal ions and a sea of delocalised electrons.
- **Wrong:** Explaining conductivity by saying 'metals have free electrons' without linking to charge movement.
  - Why it fails: Examiners require you to state that free electrons carry electrical charge through the lattice to get full marks.
  - Correct: Add that delocalised electrons are free to move and carry electrical charge when a potential difference is applied.
- **Wrong:** Explaining malleability by saying 'metallic bonds are weak'.
  - Why it fails: Metallic bonds are generally strong, and sliding layers do not break the bonds. This incorrect statement loses marks.
  - Correct: Explain that layers of positive ions slide over each other, while delocalised electrons maintain electrostatic attraction between layers so the lattice does not break.

## Cheatsheet

| Concept | Key Exam Facts to Recall |
| --- | --- |
| 2D Metallic Lattice Diagram | Regular rows of positive $M^+$ ions, explicitly labelled delocalised electrons |
| Metallic Bonding Definition | Strong electrostatic attraction between positive ion lattice and delocalised electrons |
| Electrical Conductivity Explanation | Delocalised electrons free to move and carry electrical charge through the lattice |
| Malleability Explanation | Layers of positive ions slide over each other without breaking electrostatic attractions |

## What's next

Now that you have mastered metallic bonding, you are ready to move on to comparative structure and bonding tasks, and later to the unit on metals, alloys and extraction. This knowledge is frequently tested in Paper 2C higher tier questions, so practice writing short answer responses using the exact specification terminology to maximise marks. You should also revise ionic and covalent bonding to answer comparison questions, which are common across structure and bonding topics.

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