Write a note on metallic solids.

(N/A) In metallic solids,there is a three-dimensional arrangement of metal ions surrounded by and held together by a sea of electrons.
The electrons are mobile and are evenly spread out in the entire crystal,and each metal atom contributes one or more electrons towards this sea of mobile electrons. Examples: $Fe, Cu, Ag, Mg$,etc.
Properties of metallic solids:
$1$. Metallic solids are good conductors of heat and electricity because of the presence of mobile electrons.
$2$. When an electric field is applied,these electrons flow through the network of positive ions. Similarly,when heat is supplied to one portion of the metal,the thermal energy is uniformly spread out by the free electrons.
$3$. Metals show lustre and colour in some cases due to the presence of free electrons.
$4$. Metals are malleable and ductile.