To determine which element in period 3 on the periodic table is a metalloid, we must examine the properties of each element listed:
1. Magnesium (Mg): Magnesium is an alkaline earth metal. It is not a metalloid but a metal, characterized by its shiny, solid state and excellent conductivity of electricity and heat.
2. Aluminum (Al): Aluminum is categorized as a post-transition metal. Although it shares some properties with metalloids, it is generally considered a metal due to its high malleability and ductility.
3. Silicon (Si): Silicon is well-known as a metalloid. It exhibits both metallic and non-metallic properties. It is a semiconductor, which makes it extremely valuable in the electronics industry.
4. Sulfur (S): Sulfur is a non-metal. It does not possess the intermediate properties that characterize metalloids and is known for its brittle nature and lack of electrical conductivity in its elemental form.
Based on the properties and classifications of the elements given, the metalloid in period 3 on the periodic table is:
Silicon (Si).
