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Chemical elements in the universe: Why do hydrogen and helium become the protagonists?
In the vastness of the universe, the composition of chemical elements demonstrates the fundamental characteristics of matter. According to the latest astronomical research, hydrogen and helium have become the most hotly explored major elements in the universe, and are more abundant than all other elements.
Abundance of elements
The abundance of an element is a measure of its presence relative to all other elements in the environment, usually expressed as mass fraction, mole fraction, or volume fraction. In the universe, hydrogen accounts for about 74% of the total mass, while helium accounts for about 24%. The dominant position of these elements in the universe comes mainly from Big Bang nucleosynthesis, when the high-energy conditions of the early universe contributed to the formation of hydrogen and helium.
Hydrogen is the most abundant element in the universe, with helium ranking second. The amount of other elements present is relatively small, even by several orders of magnitude.
The formation and production of elements
In the universe, hydrogen and helium were formed within minutes of the Big Bang. These elements were the first to be formed, and subsequent heavy elements were produced mainly through nucleosynthesis processes in supernovae and red giant stars. This leads to an interesting phenomenon in the universe, namely that elements with even atomic numbers are generally more abundant than their neighboring elements with odd atomic numbers, a phenomenon known as the Odor-Huggins rule.
Elemental composition on Earth
As part of the solar system, the Earth was formed from the same cloud of material, but as the planet evolved, its elemental composition changed to varying degrees. The earth's surface is mainly composed of two elements, oxygen and silicon, with a total proportion of 74.7%, and the remaining elements exist in lower proportions.
Although hydrogen and helium are the most abundant elements in the universe, Earth's composition bucks this trend, showing the profound impact of volcanic activity and geochemical processes.
Chemical interactions and environmental impacts
The abundance of an element is affected not only by its own nucleosynthetic history, but also by the chemical interactions of its environment. Therefore, in different environments, such as the atmosphere, oceans and living organisms, the composition of elements changes accordingly. Take Earth's oceans, for example. The ratio of oxygen to hydrogen shows the dominance of water, while other elements in the ocean are relatively scarce.
Chemical elements from a cosmic perspective
When we look at more distant galaxies, we find that their elemental compositions are similar to hydrogen and helium, the chemical partners of the earliest universe. This is why astronomers use metallization to describe the chemical evolution of galaxies. Metalization refers to the amount of heavy elements other than hydrogen and helium present in these galaxies.
Conclusion
Ultimately, hydrogen and helium's starring role, and their resulting abundance among all other elements in the universe, are key to scientists' understanding of the formation and evolution of the universe. However, does this composition also indicate the formation process of other stars? Are there elements waiting in some corners that we haven't discovered yet?
