How can two atoms of the same chemical element be different? a. they may be different isotopes of the element. each isotope of the same element has a different number of electrons. b. they may be different isotopes of the element. each isotope of the same element has a different number of neutrons. c. they may be different allotropes of the element. each allotrope of the same element has a different number of electrons. d. they may be different allotropes of the element. each allotrope of the same element has a different number of neutrons.