The elements that compose our universe are broadly categorized into two groups: metals and nonmetals. Metals, which make up the majority of the Periodic Table, are found to the left and center, and are known for their conductivity and luster. Nonmetals are clustered on the upper right side and are characterized by their poor conductivity. While these two groups possess distinct properties, focusing solely on these contrasts overlooks their fundamental similarities. Both metals and nonmetals share the capacity for varied physical states, act as necessary participants in chemical bonding, and are required for biological function.
Shared Physical States at Room Temperature
The physical condition of elements at standard room temperature is one point of unexpected commonality between the two major groups. Most metals, such as iron and gold, exist as dense, solid structures. However, nonmetals also include several solids, such as carbon in its various forms and sulfur, demonstrating that the solid state is not exclusive to metals.
Beyond the solid state, both categories contain a rare example of a liquid element at room temperature. Mercury is the only metal that is a liquid under these conditions. Similarly, the nonmetal bromine is the single nonmetal element that exists as a liquid at the same temperature. This overlap highlights that neither group is entirely confined to a single physical phase.
Universal Participation in Compound Formation
The most profound similarity between metals and nonmetals lies in their shared drive to achieve stability by forming chemical compounds. While they employ different mechanisms, both groups are fundamentally reactive components in nearly all chemical structures. Metals typically achieve stability by losing electrons to form positive ions, whereas nonmetals tend to gain or share electrons to form negative ions or molecular bonds.
This difference in electron behavior is a means to the same end: participation in chemical bonding to create new substances. When metals and nonmetals combine, they form ionic compounds, where the attraction between oppositely charged ions holds the structure together, such as in table salt (sodium chloride). When nonmetals combine with other nonmetals, they share electrons to form covalent compounds, creating the vast array of organic matter. The capacity to be an essential building block is a unifying feature.
A specific example of their universal participation is the formation of oxides, compounds created with oxygen. Nearly all elements, whether metal or nonmetal, react with oxygen to form an oxide. For instance, the metal sodium forms a basic oxide, while the nonmetal sulfur forms an acidic oxide. The shared capacity of both metals and nonmetals to react with oxygen confirms their fundamental role in environmental chemistry.
Indispensable Presence in Biological Function
A primary similarity that impacts all life on Earth is the shared role both metals and nonmetals play in biochemistry. Living organisms require a precise balance of elements from both categories to function. Nonmetals, including carbon, hydrogen, oxygen, and nitrogen, form the structural backbone of all organic molecules, such as DNA, proteins, and carbohydrates.
A variety of metals are also required for life processes, often in the form of ions or trace elements. Metals like sodium and potassium are necessary for the transmission of nerve signals across cell membranes. Iron is a component of hemoglobin, which is responsible for oxygen transport in the blood. Other metals like calcium and magnesium are required for structural integrity in bones and for the proper function of numerous enzymes that catalyze biochemical reactions. The necessity of both metal and nonmetal elements for structure, signaling, and energy production confirms their shared biological importance.