The chemical elements that make up all living organisms, including the human body, have formed through processes in the universe and have existed for billions of years.
The Formation of Chemical Elements in the Universe
About 14 billion years ago, the Big Bang created a universe composed entirely of gas, without stars or planets. This gas primarily consisted of atoms of the simplest elements, with about 75% being hydrogen and the remainder mostly helium, lacking elements like carbon, oxygen, nitrogen, as well as iron, silver, or gold.
In regions with a higher density of gas, gravitational forces continuously attracted more gas, eventually forming a massive gas sphere that collapsed under its own gravity and heated up from within. The core of this gas sphere became hot enough to initiate nuclear fusion, where hydrogen atoms reacted with one another to form helium while simultaneously releasing energy strong enough to counteract the pull of gravity. When the energy released from nuclear fusion balanced the gravitational force pulling all the gas inward, a state of equilibrium was achieved. As a result, a star was born.
Chemical elements in the universe are formed in the core of stars. (Source: NASA).
Nuclear fusion in the cores of stars not only produces helium but also carbon, oxygen, nitrogen, and all other elements up to iron in the periodic table. A star will completely collapse when its core runs out of fuel, resulting in a powerful explosion known as a supernova explosion. There are two important points to note about how supernova explosions create elements. First, the explosion releases so much energy that it triggers a powerful fusion process, forming heavier elements than iron, such as silver, gold, and uranium. Second, all the elements accumulated in the star’s core, such as carbon, oxygen, nitrogen, and iron, as well as those formed during the supernova explosion, are expelled into interstellar space, where they mix with existing gases.
This process then repeats. The gas cloud now contains many elements beyond just hydrogen and helium. It begins to develop denser regions that attract more matter and ultimately form a new star. Our Sun was born in this manner about 5 billion years ago, meaning it was formed from a gas cloud enriched by the elements produced in supernova explosions since the beginning of the universe. The Sun is composed of 71% hydrogen, 27% helium, and the remaining 2% consists of other elements.
The Elements on Earth
Planets also formed from gas clouds in the universe. Smaller planets like Earth lack the gravitational force to retain significant amounts of hydrogen or helium, as both are very light. They gradually escape into space. Thus, although heavier elements like carbon, nitrogen, and oxygen only make up 2% of the gas cloud that formed Earth, they are retained and constitute the primary components of Earth today.
Consider this: apart from hydrogen and some helium, the ground beneath your feet, the air you breathe, and you yourself are all made up of atoms formed within stars. When science began to explore this issue in the first half of the 20th century, the renowned American astronomer Harlow Shapley remarked: “We are the cousins of rocks, and kin to clouds.”
What is a Chemical Element? A chemical element, often simply referred to as an element, is a pure chemical substance consisting of a single type of atom, distinguished by its atomic number, which is the number of protons in each nucleus. The lightest elements are hydrogen (which has three isotopes: hydrogen, deuterium, and tritium), which were the first elements to appear in the Big Bang. All heavier elements are found or produced naturally or artificially through various methods of nuclear synthesis. Each chemical element has a unique name and symbol for easy identification. The official names of chemical elements are determined by the International Union of Pure and Applied Chemistry (IUPAC). Chemical elements are also assigned a standardized chemical symbol based on their names, mostly derived from Latin. The chemical symbols are standardized and understood worldwide, while their common names, when translated into other languages, often differ. |
