Why are hydrogen, helium and lithium important and how did these elements come to be on Earth?
The lightest elements (hydrogen, helium, deuterium, lithium) were produced in the Big Bang nucleosynthesis. According to the Big Bang theory, the temperatures in the early universe were so high that fusion reactions could take place. Stars fuse elemental hydrogen into helium in their cores. Two atoms of hydrogen are combined in a series of steps to create helium-4. These reactions account for 85% of the Sun’s energy. The remaining 15% comes from reactions that produce the elements beryllium and lithium.
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