Final answer:
An alkaline earth metal with 6 energy levels refers to barium, which is found in the sixth period of Group 2 on the periodic table and has the atomic number 56.
Step-by-step explanation:
The student is asking about an alkaline earth metal that 'has 6 energy levels'. Energy levels can be understood as an element's 'shells' or 'orbitals', and the number of these levels is indicated by the period in which the element is located on the periodic table. The alkaline earth metals are found in Group 2 of the periodic table and include elements such as beryllium, magnesium, calcium, strontium, barium, and radium.
To identify an alkaline earth metal with 6 energy levels, we should look in the sixth period of Group 2 on the periodic table. The element that meets this criterion is barium, with an atomic number of 56. Barium indeed has 6 occupied energy levels (shells) in its electron configuration, and has two electrons in its outermost s subshell, which is characteristic of alkaline earth metals.
Alkaline earth metals, like barium, are known to form basic or alkaline solutions, hence their name. Barium compounds are used in various applications including pyrotechnics and as a contrast agent for X-ray imaging of the gastrointestinal tract.