The identity of every atom is determined by its nucleus, a dense, positively charged core composed of protons and neutrons. The number of protons is the single factor that defines an element, from the lightest to the heaviest. This count is the fundamental basis for all chemistry and physics. Finding the element with the most protons means identifying the substance that currently occupies the highest slot on the periodic table, a position continually being pushed outward by scientific discovery.
The Definition of an Element by its Proton Count
The concept of an element is dependent on the quantity of protons contained within its atomic nucleus. Scientists refer to this count as the atomic number, represented by the letter Z. Every element on the periodic table has a unique atomic number, which functions like a chemical fingerprint.
For example, an atom with six protons is carbon, while an atom with eight protons is oxygen. The number of neutrons can vary, creating different isotopes of the same element. The number of electrons can also change, resulting in an ion, but neither of these changes the element’s core identity.
Identifying the Element with the Highest Proton Count
The element currently holding the record for the most protons is Oganesson (Og), which possesses 118 protons. This synthetic element occupies the final position in the seventh period of the periodic table. Since it does not occur naturally on Earth, Oganesson must be created in a laboratory.
Its atomic number of 118 places it in Group 18, the noble gases. Theoretical models suggest Oganesson is highly unstable and likely a solid or liquid at room temperature, deviating significantly from lighter noble gases like neon or argon. The International Union of Pure and Applied Chemistry (IUPAC) officially recognized its discovery and approved its name in 2016, honoring the Russian nuclear physicist Yuri Oganessian.
Oganesson is characterized by extreme radioactivity and an incredibly brief existence. The most stable known isotope, Oganesson-294, has a half-life of only around 0.7 milliseconds before it decays into a lighter element. Only a handful of atoms have ever been successfully produced, making it impossible to study its chemical properties directly. Its properties and behavior are determined through theoretical calculations and the analysis of its decay products.
Synthesizing Superheavy Elements
Elements heavier than uranium (92 protons) are synthetic, created using high-energy physics techniques. These superheavy elements, including Oganesson, are created one atom at a time in specialized research facilities. The process relies on a technique called a fusion-evaporation reaction, which requires a powerful particle accelerator.
This method involves accelerating a beam of lighter, positively charged ions (the projectile) toward a target material made of a heavy element. For the synthesis of Oganesson, researchers accelerated ions of Calcium-48, which contains 20 protons, into a Californium-249 target, which holds 98 protons.
When the two nuclei fuse, they briefly form a highly excited, combined nucleus with 118 protons. This unstable nucleus immediately releases excess energy by “evaporating” a few neutrons, resulting in a single atom of Oganesson-294. The success rate of this nuclear collision is extremely low, which is why confirming a new superheavy element often takes years of repeated experiments.
The Theoretical Limit of the Periodic Table
The existence of Oganesson raises the question of whether scientists can create elements with even more protons. The limit to the number of protons an atom can hold is due not to laboratory constraints but to the fundamental forces of nature. As the number of protons increases, the electromagnetic repulsion between the positive charges grows dramatically.
This repulsive force quickly overwhelms the strong nuclear force, which acts only over very short distances to hold the nucleus together. For elements with very high atomic numbers, the nucleus approaches immediate fission, imposing a theoretical boundary on the periodic table. However, nuclear theory suggests a possible reprieve from this trend in a region known as the “Island of Stability.”
This “island” is a predicted set of superheavy isotopes that may have significantly longer half-lives than their neighbors. The increased stability is thought to occur at “magic numbers” of protons and neutrons that correspond to completely filled energy shells within the nucleus, similar to the stability conferred by filled electron shells in noble gases. Scientists are currently targeting elements like Unbinilium (Z=120) or Unbihexium (Z=126), hoping to create the next long-lived element.