How Many Elements Are There?

Introduction

How many different basic building blocks make up the universe? For most of history nobody knew. Ancient thinkers suggested four "elements" — earth, water, air and fire — but none of these is an element in the modern sense. Today chemists have identified 118 elements , and each one has been confirmed by careful experiments. This page looks at how that number was reached and how scientists decide that a new element really exists.

Core explanation

The number today. There are 118 known elements , with atomic numbers from 1 (hydrogen) to 118 (oganesson). Because each element has a different atomic number, and every whole number from 1 to 118 is filled, there are no missing elements in this range. Any new element would need an atomic number of 119 or more.

How the list grew. Some elements, such as gold, silver, copper, iron, lead, tin, carbon and sulfur, were known in ancient times because they occur naturally as elements or are easy to extract. The number grew quickly as new methods appeared:

Around Approximate number known What made the difference --- --- --- Ancient times about 9–10 Metals and non-metals found free in nature 1800 about 30 Careful chemical analysis 1869 63 Electrolysis and spectroscopy; Mendeleev builds his table 1940 about 90 Nearly all natural elements found 2016 118 Nuclear reactions in particle accelerators

How new elements are made. The heaviest elements do not occur naturally. Scientists make them by firing a beam of lighter nuclei at a target of heavier atoms in a particle accelerator. Very occasionally two nuclei fuse to form a new, heavier nucleus. Only a handful of atoms may be produced in weeks of experiments, and they often decay in less than a second.

How a claim is confirmed. A laboratory that believes it has made a new element publishes its evidence. A joint working party of IUPAC and the International Union of Pure and Applied Physics then checks whether the evidence is convincing — usually by looking at the chain of radioactive decays that leads from the new atom to known atoms, and whether the result has been reproduced. Only then is the discovery credited.

Naming. The discoverers propose a name and a symbol, which IUPAC reviews and approves after a period for public comment. Elements 113, 115, 117 and 118 were named in 2016: nihonium (Nh), moscovium (Mc), tennessine (Ts) and oganesson (Og).

Step-by-step reasoning

How a new element enters the official list:

1. A team creates a few atoms by fusing nuclei in an accelerator. 2. They detect the atoms through their characteristic decay chain. 3. They publish the results so others can check them. 4. An independent IUPAC–IUPAP panel reviews the evidence and, if satisfied, assigns credit. 5. The discoverers propose a name and symbol, which IUPAC approves.

Visual explanation

Picture a long row of numbered seats from 1 to 118. Every seat is now occupied by an element, with no gaps. Seat 119 and beyond are empty, waiting for elements that have not yet been made and confirmed.

Real-world analogy

Confirming a new element is like a sports record being ratified. An athlete may run a record time, but officials check the timing equipment, the wind speed and the rules before it becomes official. A claimed element is likewise checked by independent experts before it is accepted.

Real-world example

Element 117, tennessine, was made by an international collaboration using a target of berkelium produced in a reactor in Tennessee, USA, and a beam of calcium nuclei in Dubna, Russia. Its name honours the region of the laboratories that helped make it.

Why?

Why is it so hard to make new elements? Nuclei are positively charged and repel each other strongly, so they must collide at great speed to fuse. Even then, most collisions fail, and the heaviest nuclei are very unstable, often decaying in thousandths of a second.

Common misconception

"There are thousands of elements, because there are thousands of different materials." Most materials are compounds or mixtures made from combinations of the same 118 elements. Around 90 of these make up almost everything we meet.

Worked example

Question: A newspaper reports that scientists have "discovered element 95". Why should a chemist doubt that this is new?

Reasoning: Every atomic number from 1 to 118 already belongs to a known element. Element 95 is americium, which has been known since the 1940s.

Answer: Element 95 is already known, so it cannot be a newly discovered element; a genuinely new element would need an atomic number of 119 or higher.

Quick check

1. What is the atomic number of the heaviest element currently confirmed? Answer: 118, the element oganesson (Og).

Exam focus

Remember the number 118 and that every element has a unique atomic number. You may be asked why elements with very high atomic numbers are not found in nature: they are radioactive with very short half-lives, so any that formed long ago have decayed.

Advanced insight

Physicists predict an "island of stability" for certain superheavy nuclei with particular numbers of protons and neutrons, where half-lives might be much longer. Reaching elements 119 and 120 would need beams of heavier nuclei such as titanium, and the chance of fusion is extremely small, so experiments may run for years.

Summary

There are 118 known elements, with atomic numbers 1 to 118 and no gaps. The number grew from about ten in ancient times through chemical analysis, electrolysis, spectroscopy and finally nuclear reactions. New elements are made in accelerators, confirmed by an independent IUPAC–IUPAP panel, and then named with IUPAC approval.

Practice questions

1. How many elements are currently known? Answer: 118. 2. Name the organisation that approves names and symbols of new elements. Answer: IUPAC, the International Union of Pure and Applied Chemistry. 3. Explain why scientists can be sure there is no undiscovered element between hydrogen and oganesson. Answer: Each element has a unique whole-number atomic number, and every number from 1 to 118 is already occupied. 4. Give one reason why only a few atoms of a superheavy element are made in an experiment. Answer: Positively charged nuclei repel each other, so fusion is very rare; also the new nuclei decay very quickly.