Steel is not found on the periodic table of elements. The periodic table serves as an organized chart for the fundamental building blocks of matter, known as pure elements. Since steel is a manufactured material created by mixing these pure substances, it does not qualify for a spot on the chart. The table is reserved exclusively for substances that cannot be broken down chemically into simpler components.
Defining the Pure Elements
The periodic table is a scientific arrangement of all known chemical elements, organized primarily by their atomic number. This number represents the count of protons found within the nucleus of an atom, which uniquely identifies each element. Every element on the table consists of atoms that all share this identical number of protons.
This organized structure allows scientists to predict an element’s behavior based on its location. The horizontal rows, called periods, correspond to the number of electron shells an atom has. Vertical columns, known as groups, contain elements that exhibit similar chemical properties because they share the same number of valence electrons in their outermost shell.
A substance is considered a pure element only if it is composed entirely of one type of atom. For instance, a sample of gold (chemical symbol Au) consists solely of gold atoms, each with 79 protons. The properties of an element are intrinsic and fixed.
Steel as a Metallic Mixture
Steel is classified as a metallic alloy, a material made by combining two or more elements, with at least one being a metal. It is primarily composed of iron (Fe on the periodic table) combined with a small amount of carbon. The carbon content is typically maintained within a range of 0.002% to 2.1% by weight.
The manufacturing process involves melting down iron and then introducing carbon and other elements into the molten metal. This mixing is carried out in large vessels like a Basic Oxygen Furnace (BOF) or an Electric Arc Furnace (EAF). The addition of carbon is crucial because pure iron is relatively soft and structurally weak.
In addition to iron and carbon, trace amounts of other elements are often added to tailor the final product’s characteristics. For example, elements like chromium or nickel are introduced to create stainless steel, enhancing its resistance to corrosion. The material’s final properties depend on the precise ratio and combination of these constituent elements.
How Elements and Alloys Differ
The core difference between an element and an alloy lies in their fundamental nature as pure substances versus mixtures. An element, like iron or carbon, is a pure substance that cannot be chemically simplified any further. Its atoms are all identical, resulting in fixed and predictable chemical and physical properties.
An alloy, such as steel, is a physical mixture where the atoms of the different elements are intermingled but not chemically bonded together to form a new compound. This combination occurs when the molten materials are mixed and cooled. Because it is a mixture, the precise composition can be varied, resulting in a range of possible properties.
While the elements within an alloy retain their original chemical identities, the resulting alloy exhibits enhanced physical properties. For example, adding carbon atoms to the iron lattice disrupts the pure metallic structure, which significantly increases the material’s hardness and tensile strength. This physical combination allows engineers to create materials with specific, superior characteristics.