Chemists can state with certainty that no one will discover an element between sulfur and chlorine because the periodic table is a fundamental framework based on the atomic structure of elements.

Here's why:

* Atomic Number: The periodic table is arranged by increasing atomic number, which represents the number of protons in an atom's nucleus. Each element has a unique atomic number.

* Electron Configuration: The periodic table also reflects the arrangement of electrons in atoms. The elements are grouped based on their electron configurations, leading to predictable chemical properties.

* Periodicity: Elements in the same vertical column (group) have similar chemical properties due to similar outer electron configurations. This is known as periodicity.

Sulfur (S) has an atomic number of 16, and chlorine (Cl) has an atomic number of 17. This means there is no possible space for an element with an atomic number between 16 and 17.

In other words, the atomic number is a continuous sequence, and there is no gap between sulfur and chlorine for another element to occupy.

Therefore, discovering a new element between sulfur and chlorine is not possible within the established framework of the periodic table and our understanding of atomic structure.