Final answer:
Iron (Fe), which exhibits metallic bonding, would be expected to have a sea of electrons surrounding nuclei. Sulfur (S), oxygen (O), and xenon (Xe) do not exhibit this property as they are nonmetals and a noble gas, respectively.
Step-by-step explanation:
The student asked which element in a given list is expected to exhibit a sea of electrons surrounding nuclei. The correct answer to this is Fe (iron), which is option number 4. This characteristic of a 'sea of electrons' refers to the metallic bonding that occurs in metals. In this type of chemical bonding, atoms in a metallic element such as iron are surrounded by a sea of delocalized, or free-moving, electrons. These electrons are not bound to any particular atom and can move freely throughout the entire structure. This results in metals having properties like ductility, malleability, and high electrical and thermal conductivity.
When we compare the given options, S (sulfur) and O (oxygen) are nonmetals, while Xe (xenon) is a noble gas. None of these elements exhibit metallic bonding or a sea of electrons. Metals like iron, which are typically found in the middle of the periodic table, are where we would expect to find such a characteristic.