Final answer:
The element referred to by the atomic number 78 is platinum, a precious metal known for its resistance to corrosion and excellent catalytic properties.
Step-by-step explanation:
The student is referring to element with the atomic number 78, which is platinum, a valuable element that is classified among the platinum metals alongside ruthenium, osmium, rhodium, iridium, and palladium. Platinum is known for its distinctive properties such as high resistance to chemical corrosion, excellent catalytic properties, and significant electrical conductivity. These platinum metals do not form stable oxyanions and are stable in the presence of water. When considering the atomic structure of elements, platinum has 78 protons in the nucleus, and the element's type or identity is determined by the number of protons it contains.