Metallic bonding · Grade 11
In a metal the atoms give up their outer electrons. This leaves a regular lattice of positive ions in a “sea” of delocalised electrons that move freely through the whole structure. The strong attraction between the positive ions and the delocalised electrons is metallic bonding, and it explains why metals conduct, bend without breaking and have high melting points.
Key facts
- Metallic bonding is the strong attraction between positive metal ions and delocalised electrons.
- Each atom gives its outer electrons to the sea: sodium gives 1, magnesium 2 and aluminium 3.
- Delocalised electrons can move and carry charge and energy, so metals conduct electricity and heat.
- The layers of ions can slide over each other, so pure metals can be hammered into shape and drawn into wires.
- Most metals have high melting points, because the metallic bonding is strong throughout a giant structure.
- An alloy is a mixture of a metal with other elements. Atoms of different sizes distort the layers so they cannot slide easily, so alloys are harder than pure metals.