The world around us is composed of countless different substances, yet all matter is built from fundamental components called atoms. Atoms are the smallest unit of a chemical element that retains its properties. The “type” of atom is determined by a specific count of its subatomic particles, leading to distinct elements. Scientists have confirmed the existence of 118 different types of atoms, which form the basis of the entire universe.
Defining the “Type” of Atom
The identity of an atom is defined by a precise number of a subatomic particle called the proton. Protons are positively charged particles located in the atom’s dense central core, known as the nucleus. The number of protons in the nucleus is called the atomic number.
This atomic number is the single characteristic that differentiates one element from another. For instance, every atom that contains exactly six protons is, by definition, a carbon atom. If an atom gains or loses a proton, it fundamentally changes its identity and becomes a different element entirely.
Changing the number of neutrons (particles with no charge also found in the nucleus) creates a different version of the same element, called an isotope. Changing the number of electrons orbiting the nucleus changes the atom’s electrical charge, making it an ion. However, the element’s identity remains tied solely to its fixed number of protons. The number of protons is the chemical fingerprint that defines each unique type of atom.
The Count: Known Elements and the Periodic Table
The current count of distinct types of atoms stands at 118, with each one corresponding to a unique atomic number from 1 to 118. This collection of elements is systematically mapped out in the Periodic Table, which serves as a comprehensive tool for organizing chemical knowledge. The table arranges elements in order of increasing atomic number, starting with Hydrogen (1 proton) and ending with Oganesson (118 protons).
As elements are positioned across the table in rows and down in columns, the arrangement reveals repeating patterns in their chemical behavior. Elements placed in the same vertical column, or group, share similar chemical properties because they have comparable arrangements of electrons in their outermost shell. The Periodic Table is a predictive framework that allows scientists to anticipate the characteristics of an element based on its position.
The table’s structure reflects a natural law, showing how the properties of atoms change periodically as the atomic number increases. This organization is a direct consequence of the proton count determining an atom’s electron structure, which dictates how it interacts with other atoms.
Natural vs. Synthetic Elements
While the official count is 118, not all of these elements exist freely or permanently in nature. The first 94 elements, from Hydrogen (atomic number 1) up to Plutonium (atomic number 94), are considered naturally occurring, although some only exist in trace amounts as products of radioactive decay.
Elements with atomic numbers greater than 94 have been created artificially in laboratories, typically by smashing atomic nuclei together in particle accelerators. These are known as synthetic or transuranic elements, and they are inherently unstable.
The instability of these laboratory-made atoms is measured by their half-life, which is the time it takes for half of the sample to decay into a different element. For the heaviest synthetic elements, this half-life can be incredibly short, sometimes lasting only milliseconds. Their sole purpose is often for scientific research, as their rapid decay prevents them from accumulating in any significant quantity.