Final answer:
Indium is a metal, placed in Group 13 of the periodic table among metals like aluminum, gallium, and thallium, and exhibits typical metallic properties such as shininess and good conductivity.
Step-by-step explanation:
Indium is indeed a metal. Based on its location in the periodic table, specifically in Group 13, indium is categorized as a metal. It is found among other metals such as aluminum, gallium, and thallium. Indium exhibits a clearly metallic character, which is illustrated by its basic oxides and hydroxides. Additionally, it is known to be a silvery-white metal that demonstrates properties typical of metals such as being shiny and a good conductor of heat and electricity.
The confusion about whether indium was a metal, nonmetal, or semimetal was clarified by Dmitri Mendeleev, who reassessed the atomic mass of elements during the development of the periodic table. Finding that indium's atomic mass was actually 113, placing it among other metals, supported its metallic nature.
Therefore, the answer to the question is that indium is a metal, and this is supported both by its properties and its placement in the periodic table.