The composition of the universe reflects this evolutionary origin, as shown in the table on page 32. The universe is 93% hydrogen and 7% helium, with all of the other elements amounting to only 0.10%. A gap in natural abundance exists between He and C, reflecting the jump in synthesis:



Lithium, beryllium, and boron are formed later in secondary reactions involving the breakup of larger nuclei. Hence they are scarce in comparison with the elements on the direct line of synthesis. Beyond carbon, there is an alternation of abundance, with atoms of even atomic numbers more common than odd, as seen on the graph on page 31. Again, this reflects the synthesis of the even elements by addition of alpha particles, . The odd elements, just like Li, Be, and B, must be made by side reactions and hence are not as prevalent. This is the primary reason why oxygen is used for the energy-producing reactions of life on Earth, even though fluorine is more electronegative; fluorine is simply too rare to be depended on as a biological oxidant. If this were not so, we probably would burn our foods with rather than , and call the process fluoridation instead of oxidation.

The universe began as an unequal mixture of elements: few atoms of high atomic number, fewer with odd atomic numbers, and almost no Li, Be, or B.