Here's why:

* Structure: Metals have a unique structure where their outermost electrons are loosely bound to their atoms. This creates a "sea" of free electrons that can easily move throughout the material.

* Conductivity: The presence of these free electrons allows for the easy flow of electric current, making metals excellent conductors of electricity. They also conduct heat very well.

Exceptions:

While most metals are conductors, there are a few exceptions:

* Mercury: Though a liquid at room temperature, mercury is a poor conductor of electricity compared to other metals.

* Lead: Lead has a relatively high resistance and is not as conductive as many other metals.

Summary:

The vast majority of metals are excellent conductors of electricity due to their unique atomic structure and the presence of free electrons.