The metalic lattice

The metal atoms, and also their ions (after losing their val electrons) have their fixed position in a lattice; they are very neatly packed and ordered, just as in an ionic lattice. But now we speak of a METALLIC LATTICE.
All those positive ions are kept toghether by the "free moving electrons".
Those (negative) electrons can be considered as a kind of glue that holds the atom ions, the metal ions, toghether in the lattice.
Those valency electrons are called 'free' because they are no longer connected to only one atom.
The attraction between the negarive free moving electrons and the positive ions in the lattice is what we call: METALLIC BOND.

Metallic bond = attraction between (negative free) electrons and (positive) metal ions in a lattice

These attraction forces can be considerably strong. But can differ per metal.
To break a lattice of Iron (i.e. to melt Iron) you need very high temperatures, but the metal Lead melt much easier. (see module 5)