Metals are materials that have all five of the following properties:
- They are malleable (reshaped by force while still in the solid state - crumpling up aluminum foil or shaping an iron bar into a horseshoe).
- They are ductile (can be drawn or extruded into wires)
- They are shiny
- They conduct heat
- They conduct electricity
Metallic solids are made of metal atoms and held together by metallic bonding.
Imagine the atoms of a metal.
To understand metallic bonding we need to remember that elements on the left side of the periodic table (where the metals are) have low ionization potentials. That means that the electrons of metal atoms are held loosely. Let's focus on just one of those electrons.
We can imagine it moving a little away from it's own nucleus and feeling the attraction of another atom's nucleus. Wandering off in that direction, it might feel the attraction of another and another.
The situation is ideal for the electron, because it feels the attraction of many nuclei. The situation also works out well for the nuclei, because all of the electrons are doing the same thing.
The end result is that each electron feels the attraction of lots of nuclei and each nucleus feels the attraction of lots of electrons.
This “sea” of electrons is what allows metals to conduct electricity.
Because metallic bonding does not require a specific arrangement of the atoms (only that they be close together). This is what makes metals malleable and ductile (the atoms can be rearranged as long as they stay close together).