Here's why:

* Metallic bonding: Metals have strong metallic bonds that allow atoms to slide past each other. This makes them ductile, meaning they can be deformed without breaking.

* Crystalline structure: The arrangement of atoms in a metal's crystalline structure also contributes to its ductility.

* Brittleness: Brittleness is the tendency of a material to fracture with little to no deformation. This is more common in non-metals like ceramics and glasses.

However, there are exceptions:

* Some metals can become brittle under specific conditions:

* Low temperatures: Metals can become brittle at very low temperatures.

* Impurities: Impurities in a metal can make it more brittle.

* High strain rates: If a metal is subjected to a very fast and forceful impact, it may fracture before it can deform.

* Certain alloys: Some alloys, like cast iron, are intentionally designed to be brittle for specific applications.

In summary: While brittleness is not a typical characteristic of metals, there are situations where metals can exhibit this behavior. It's important to understand the specific metal and its environmental conditions to determine its ductility or brittleness.