Final answer:
The lucky number for each element is the number of electrons needed to fill its valence shell, similar to the noble gases with full shells.
Step-by-step explanation:
The "lucky number" that every element seeks to have generally refers to the concept of having a full valence shell, much like the noble gases. These elements are known for their chemical stability due to having a full outer shell of electrons, which most other elements strive to emulate through chemical bonding. Atoms often gain, lose, or share electrons to achieve the same number of electrons as the noble gas closest to them in the periodic table.
An element's identity is defined by its number of protons, known as the atomic number, and each element aims to have a number of electrons equal to its atomic number to be electrically neutral. For example, hydrogen with an atomic number of 1 naturally has one electron when neutral, while iron with an atomic number of 26 will have 26 electrons when neutral.
The concept of the "island of stability" also touches on the idea that certain higher atomic number elements (superheavy elements) with particular numbers of protons and neutrons may be more stable than others, possibly possessing longer-lived isotopes despite high atomic numbers. This theoretical stability is hypothesized to occur at atomic numbers near the 'magic number' 126, and for neutrons, the next magic number is predicted to be 184.