Final answer:
The delay in recognition of Tennessine as a new element until 2015 likely resulted from the rigorous verification protocols in the scientific community, requiring independent confirmation and replication of the discovery before acceptance.
Step-by-step explanation:
Tennessine, also known as element 117, was first identified in 2010 by a group of scientists. It was not accepted as a new element by the scientific community until 2015, possibly due to the stringent verification processes required for such a discovery. Element discovery is a meticulous process that often involves independent replication and confirmation of the results by other researchers. This is critical to ensure that the observed element is indeed a new entity and that the observed data is not due to an experimental error or other interfering factors.
The acceptance of new elements into the periodic table is overseen by organizations such as the International Union of Pure and Applied Chemistry (IUPAC), which require extensive peer review and multiple confirmed observations of the element's properties before official recognition. In historical context, even the periodic table designed by Dmitri Mendeleev took years before being universally accepted and integrated with emerging scientific discoveries, such as adding the noble gases or recognizing the significance of atomic number over atomic mass.
The discovery of isotopes also played an important role in understanding that some elements might have been misidentified in the past due to differing atomic masses, yet still be chemically identical. These factors contribute to the caution exercised by the scientific community before new elements, like Tennessine, are officially recognized.