A scientist determines that an element has a high reactivity and a large atomic radius. What other properties does the element most likely have?

your parents i think this could be it

it's c (engineer's do their work with mechanical stuff not on any living being)

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.