The elements that compose our world are categorized into metals, nonmetals, and metalloids based on their physical and chemical properties. This classification system, organized within the periodic table, determines how an element behaves. Barium, represented by the atomic symbol Ba and atomic number 56, is often questioned regarding its place in this system. Understanding its nature requires examining its position on the table and its atomic structure.
Barium’s Identity and Classification
Barium is classified as a metal and is a member of the Alkaline Earth Metals family. This designation places it in Group 2 of the periodic table, alongside elements like magnesium and calcium. Elements in this group are highly reactive, meaning Barium is never found in its pure, elemental state in nature. It exists only in compounds, such as the minerals barite (barium sulfate) and witherite (barium carbonate).
Barium’s position in the sixth period and second group reveals its electron configuration. It possesses two valence electrons in its outermost shell (6s²), a structure common to all Alkaline Earth Metals. This arrangement causes Barium to readily lose these two electrons to achieve a stable configuration, forming a cation with a charge of +2. This tendency to donate electrons and form positive ions is a key chemical property of metallic elements.
Defining Characteristics of Barium
The physical attributes of Barium provide evidence that it belongs to the metallic class. In its pure, unoxidized state, Barium is a soft, silvery-white metal that can be easily cut with a knife. It exhibits a low Mohs hardness of approximately 1.25. Barium is also an efficient conductor of both heat and electricity, a property derived from the free movement of its valence electrons.
Its density is relatively low for a heavy metal, registering around 3.51 to 3.62 grams per cubic centimeter at standard state. The melting point of Barium is approximately 727 degrees Celsius, consistent with its group. Chemically, Barium is highly electropositive, meaning it has a strong drive to lose electrons, contributing to its reactivity.
Barium reacts vigorously with water at room temperature, producing Barium hydroxide and releasing hydrogen gas. It also oxidizes rapidly when exposed to air, quickly forming a dark gray layer of Barium oxide on its surface. This high chemical affinity for nonmetals, such as oxygen and halogens, and its ability to achieve a stable +2 oxidation state solidify its classification as a reactive metal.
Common Uses and Safety Considerations
Barium compounds have several important applications across various industries. Barium sulfate (BaSO₄) is widely used in medical imaging as a radiocontrast agent for X-ray and CT scans of the gastrointestinal tract. Given orally in a suspension, it coats internal organs, making them visible on an image. Barium salts, such as barium nitrate, are also used in pyrotechnics to generate a bright green color in fireworks.
Barium compounds are also utilized in the oil and gas industry to increase the density of drilling fluids, which helps stabilize the well during the drilling process. When considering safety, it is important to distinguish between soluble and insoluble Barium compounds. While most soluble Barium compounds, like Barium chloride, are highly toxic and can cause serious health issues if ingested, the insoluble Barium sulfate used in medicine is safe. Barium sulfate is non-toxic because its low solubility prevents it from being absorbed into the bloodstream as it passes through the digestive system.