Question

Which one of the following is a metalloid?
${\text{A}}{\text{.}}$ Na
${\text{B}}{\text{.}}$ S
${\text{C}}{\text{.}}$ Si
${\text{D}}{\text{.}}$ F

Answer 1

Hint- Here, we will be discussing the classification of elements into metals, nonmetals and metalloids. Then, we will be observing all the options given in the problem one by one and find out which one of these exhibits the same properties as those of metalloids.
The elements can be classified as metals, non-metals, or metalloids.
Metals are good conductors of heat and electricity, and are malleable (they can be hammered into sheets) and ductile (they can be drawn into wire). Most of the metals are solids at room temperature, with a characteristic silvery shine (except for mercury, which is a liquid).
Non-metals are (usually) poor conductors of heat and electricity, and are not malleable or ductile; many of the elemental nonmetals are gases at room temperature, while others are liquids and others are solids.
The metalloids are intermediate in their properties. In their physical properties, they are more like the non-metals, but under certain circumstances, several of them can be made to conduct electricity. These are referred to as semiconductor elements. These semiconductors are extremely important in computers and other electronic devices.
Since most metalloids tend to display semiconducting properties in at least one of their allomorphic modifications, the class might reasonably be extended to also include gray silicon (which, unlike white silicon, is a semiconductor rather than a metal) and the graphite form of carbon (which, unlike the diamond form, is a semimetal rather than an insulator). Chemically, metalloids correspond to atoms having intermediate electronegativities and an ability to display a range of both positive and negative oxidation states in their compounds.
Sodium (Na): Sodium is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in period 3 and group 1 of the periodic table.
Sulfur (S): Sulfur is characterized as a non-metal because it is consistent with the physical properties listed for non-metals. It is a poor conductor of heat and electricity because the electrons are not free to move. It is located corresponding to period 3 and group 16.
Silicon (Si): It is a metalloid because it exhibits properties similar to any semiconductor material. It is located corresponding to period 3 and group 14.
Fluorine (F): It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive, as it reacts with all other elements, except for argon, neon, and helium. It is located corresponding to period 2 and group 17.
Therefore, silicon (Si) is a metalloid out of Na, S, Si and F.
Hence, option C is correct.

Note- The term is normally applied to a group of between six and nine elements (boron, silicon, germanium, arsenic, antimony, tellurium, bismuth, polonium, astatine) found near the centre of the P-block or main block of the periodic table. Grey silicon and graphite form of carbon both are semiconductors in nature.