What properties do metals have in common?
Metals conduct electricity, are ductile, malleable and have a "metallic" luster. Metals also form positive ions.
Because metals have a low electronegativity the electrons are not held tightly to the atoms. The loosely held electrons are able to shift and move positions.
This ability of the electrons creates the so called sea of electrons. The sea of electrons creates metallic bonding. The fact that electrons can be rearranged explains the malleability of metals ( that they can be hammered flat) and the ductility of metals (that they can be stretched into wires.
The sea of electrons creates the shimmer of electrons that is observed as metallic luster. The sea of electrons also explains how metals are able to conduct electricity.
Because metals have a low electronegativity the metals lose electrons creating a positive charge.