Positive ions in a sea of delocalised electrons, why metals conduct and bend, and why alloys are harder.
What you will learn
- Describe metallic bonding
- Explain why metals conduct electricity and heat and can be shaped
- Explain why alloys are harder than pure metals and calculate alloy compositions
A sea of electrons
In a metal the outer electrons of each atom are not tied to that atom.
They are delocalised: free to move through the whole structure. What is left are positive ions in a regular lattice. Metallic bonding is the strong attraction between the positive ions and the shared sea of electrons.
A Group 2 metal such as magnesium gives two electrons per atom to the sea, so the lattice is made of Mg2+ ions. Each atom gives as many electrons as its group number, so 3.0 × 10²⁰ magnesium atoms give 2 × 3.0 × 10²⁰ = 6.0 × 10²⁰ delocalised electrons.
The rest of this lesson and its 10 practice questions are locked.
In this lesson
- A sea of electrons
- Properties from the structure
- Alloy calculations
- Try it: Carats
10 practice questions, marked as you go; about 20 minutes in all.
Key terms
Positive ions, Alloy
In this unit: Bonding, structure and the properties of matter
Ionic, covalent and metallic bonding, the structures they make, and how structure explains melting points, conduction and hardness, with nanoparticles for separate Chemistry.