Question

atomic radius is ______. the distance from the center of the nucleus to the outermost electron. the distance from center of the nucleus to the first energy level. the distance from one outer electron to another outer electron. the distance from one proton to one electron.

Explanation:

Atomic radius is defined as the distance from the center of the nucleus to the outermost electron. This is a fundamental concept in chemistry related to the size of an atom. The other options are incorrect: the first energy level is not the outermost in most atoms; measuring from one outer electron to another does not define the atomic radius as it's about the atom's own structure relative to its nucleus; and measuring from a proton to an electron in that way is not the standard definition.

Answer:

the distance from the center of the nucleus to the outermost electron.