Metalloids exhibit the physical and chemical properties of both metals and non-metals on the periodic table. They may display certain properties of metal or non-metals when reacting with certain chemicals.
The physical properties of metalloids are those that can be observed without any change to the metalloid itself. This includes the material's luster, elasticity, conductivity and color. Metalloids are solid semi-conductive materials and react differently based on the element to which they're exposed.
For example, boron is a metalloid that acts as a non-metal with sodium, while acting as a metal when exposed to fluorine. The variations in density, boiling points and melting points of metalloids greatly affect their reactions to external influences.