What is Metal?
Metal is a term that can refer to different types of substances with various properties and uses. In chemistry, a metal is a chemical element that has a shiny appearance, conducts electricity and heat well, and can be shaped into thin sheets or wires. In physics, a metal is any material that can conduct electricity at very low temperatures. In astronomy, a metal is any element heavier than helium that forms in stars.
Some examples of metals are iron, copper, gold, silver, and aluminum. Metals can be pure elements or mixtures of elements called alloys. For instance, stainless steel is an alloy of iron, carbon, and chromium. Metals can also form compounds with nonmetals, such as metal oxides and metal sulfides.
Metals have many applications in various fields, such as construction, transportation, communication, medicine, and art. Metals are also essential for life, as some metals are involved in biological processes such as enzyme catalysis, oxygen transport, and nerve signaling.
How are Metals Classified?
Metals can be classified based on different criteria, such as their atomic structure, their composition, their physical properties, or their uses. Here are some common ways of classifying metals:
- Based on atomic structure: Metals can be grouped according to their position in the periodic table, which reflects their electronic configuration and chemical behavior. Some common groups are alkali metals, alkaline earth metals, transition metals, rare earth metals, and post-transition metals. For example, alkali metals are highly reactive and have one electron in their outermost shell, while transition metals are less reactive and have multiple electrons in their outermost shell.
- Based on composition: Metals can be divided into pure metals and alloys. Pure metals are elements that consist of only one type of atom, such as iron, copper, or gold. Alloys are mixtures of two or more metals or metalloids, such as steel, brass, or bronze. Alloys usually have different properties than their constituent elements, such as higher strength, lower melting point, or better corrosion resistance.
- Based on physical properties: Metals can be categorized according to their physical characteristics, such as hardness, density, melting point, conductivity, or magnetism. For example, hard metals are resistant to deformation and abrasion, while soft metals are easily cut or shaped. Dense metals have high mass per unit volume, while light metals have low mass per unit volume. High melting point metals can withstand high temperatures without melting or vaporizing, while low melting point metals melt or vaporize at relatively low temperatures. Conductive metals allow the flow of electricity or heat through them, while non-conductive metals do not. Magnetic metals are attracted by a magnet or can become magnetized themselves, while non-magnetic metals are not.
- Based on uses: Metals can be classified according to their applications in various fields, such as construction, transportation, communication, medicine, or art. For example, structural metals are used for building bridges, buildings, or vehicles; electrical metals are used for making wires, cables, or circuits; biomedical metals are used for making implants, prosthetics, or instruments; and decorative metals are used for making jewelry, coins, or sculptures.