The periodic table serves as an organized map of all known chemical elements, arranging them based on their atomic number, electron configurations, and recurring chemical properties. This systematic arrangement allows scientists to categorize elements into broad groups, which helps in understanding their behavior and interactions. While the table primarily showcases metals, a significant portion of elements fall into other classifications, including nonmetals.
The Number of Nonmetals
There are 17 elements widely recognized as nonmetals on the periodic table. These include:
- Hydrogen (H)
- Carbon (C)
- Nitrogen (N)
- Oxygen (O)
- Phosphorus (P)
- Sulfur (S)
- Selenium (Se)
- Fluorine (F)
- Chlorine (Cl)
- Bromine (Br)
- Iodine (I)
- Astatine (At)
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Radon (Rn)
Some classifications may extend this count to 18 or 19 elements by including the superheavy elements Tennessine (Ts) and Oganesson (Og), whose chemical properties are largely theoretical but predicted to be nonmetallic.
Defining Nonmetals
Nonmetals exhibit distinct physical and chemical characteristics. Physically, nonmetals are typically poor conductors of heat and electricity, with the notable exception of graphite, an allotrope of carbon. In their solid form, nonmetals are generally brittle, meaning they cannot be hammered into sheets or drawn into wires without breaking. They also tend to have a dull appearance rather than the shiny luster associated with metals.
Nonmetals exist in various states at room temperature: some are gases like oxygen and nitrogen, bromine is a liquid, and others such as carbon, sulfur, and iodine are solids. Compared to metals, nonmetals generally possess lower melting and boiling points and lower densities. Chemically, nonmetals are characterized by their tendency to gain or share electrons in chemical reactions. They typically have high electronegativity, indicating a strong attraction for electrons, and high ionization energies, which means a significant amount of energy is required to remove an electron from them. When nonmetals react with oxygen, they often form oxides that are acidic or neutral in nature.
Nonmetals’ Position on the Periodic Table
Nonmetals are predominantly found on the upper right side of the periodic table. Their location is visually delineated from the metals by a distinctive “staircase” or “zigzag” line. Elements that lie directly along this separating line are known as metalloids, which display properties intermediate between those of metals and nonmetals.
An important exception to this general placement is hydrogen, which is situated in the upper left corner of the periodic table. Despite its position, hydrogen’s properties classify it as a nonmetal. The arrangement of nonmetals on the periodic table reflects their electron configurations, which influences their chemical reactivity. Elements in this region typically have outer electron shells that are nearly full, leading to their characteristic behavior of gaining or sharing electrons to achieve stability.