Question

According to the Oddo-Harkins rule, chemical elements with even atomic numbers are more abundant than elements that have odd atomic numbers. Examine Figure 4.5 and note the elements Al, Si, and P. Determine whether these elements obey the Oddo-Harkins rule and suggest an explanation for this phenomenon.

Answer 1

Let Z = atomic number = number of protons in the nucleus of an atom

Z (Al) = 13, Z (Si) = 14, Z (P) = 15

Indicates that Si (Z = 14) is more abundant than Al (Z = 13) and P (Z = 15). Therefore, these elements obey the Oddo-Harkins rule.

The cause of this relationship is that nuclei having an even number of protons are more stable than atoms that contain an odd number of protons. During nucleosynthesis in stars, atoms that are especially stable have a better chance to survive than atoms whose nuclei are less stable.