Question

Classify each of the following materials as metal, semiconductor, or insulator: (a) InAs (b) \(\mathrm{MgO}\) (c) \(\mathrm{HgS}\) (d) Sn

Short answer

(a) InAs is a semiconductor. (b) MgO is an insulator. (c) HgS is an insulator. (d) Sn is a metal.

Step-by-step solution

(a) InAs

InAs is a compound formed by combining Indium (In), which is a metal, and Arsenic (As), which is a metalloid (semiconductor). The combination of a metal and a metalloid leads to a semiconductor. Therefore, InAs is classified as a semiconductor.

(b) MgO

MgO is a compound formed by combining Magnesium (Mg), which is a metal, and Oxygen (O), which is a non-metal. Metals typically form ionic bonds with non-metals, which in turn leads to insulating materials due to the non-conductive nature of such compounds. Hence, MgO is classified as an insulator.

(c) HgS

HgS is a compound formed by combining Mercury (Hg), which is a metal, and Sulfur (S), which is a non-metal. Similar to the case of MgO, metals typically form ionic bonds with non-metals, and this leads to insulating materials due to the non-conductive nature of such compounds. Therefore, HgS is classified as an insulator.

(d) Sn

Sn is the chemical symbol for Tin, which is a chemical element found on the left side of the periodic table, in the metal group. As it is not combined with any other element and is a pure metallic element, Sn is classified as a metal. In summary, InAs is a semiconductor, MgO and HgS are insulators, and Sn is a metal.

Key concepts

Metals

Metals are elements known for their shiny appearance and good electrical conductivity. They occupy a large portion of the periodic table and are often found on the left side. These materials are great conductors because they have free-moving electrons, which allows electricity to flow through them easily.

Key properties of metals include:

• High electrical and thermal conductivity
• Malleability and ductility (can be shaped and stretched)
• Metallic luster (shiny surface)

A familiar example of a metal is Tin (Sn), like the one mentioned in our exercise. Being a "pure metal," Tin displays all the characteristics typical of this material. Metals are used extensively in construction, transportation, and electronic industries due to their favorable properties.

Moreover, since metals can easily transfer energetic electrons from atom to atom, they also serve as excellent catalysts in various chemical reactions. Understanding these characteristics of metals helps in effectively utilizing their potential in technological applications.

Semiconductors

Semiconductors are fascinating materials that lie somewhere between metals and insulators when it comes to electrical conductivity. Unlike metals, they don't let electricity flow freely, but unlike insulators, they aren't completely resistant either. Instead, their conductivity can be altered by introducing certain elements or conditions.

In the case of InAs (Indium Arsenide), which is highlighted in our exercise, it serves as a prime example of a semiconductor. It is constructed from a combination of a metal and a metalloid, which grants it its semiconducting properties.

• Critical part of modern electronics, aiding components like diodes, transistors, and solar cells.
• Conductivity can be modified with the process called "doping," where small amounts of other elements are introduced.
• Useful in controlling electrical currents, making them valuable in computers and various electronic devices.

This ability to precisely control electrical conductance makes semiconductors integral to technology fields, driving innovations in microelectronics and beyond.

Insulators

Insulators are those materials that do not conduct electricity well. These materials have tightly bound electrons, which make it difficult for them to move freely, thus preventing an electric current from passing through easily. Examples of insulators from our exercise include compounds like MgO (Magnesium Oxide) and HgS (Mercury(II) Sulfide).

The characteristics of insulators include:

• Low electrical conductivity
• High resistance to electrical flow
• Often used to protect against the unwanted passage of electricity

Insulators serve essential functions in everything from simple household products to complex electronics. They are crucial in ensuring that electrical currents flow in the direction they are meant to and prevent any accidental conducts that may cause harm or decrease efficiency. For instance, cables and electrical wirings often use insulators to safeguard the conductive materials inside and protect users from electrical shocks. In science and industry, understanding insulators offers insights into maintaining safety and controlling energy applications efficiently.