Question

which element does not have the same number of electrons in its outermost shell as the other elements in its group? (1 point)
o bromine (br)
o boron (b)
o hydrogen (h)
o helium (he)

Explanation:

Step1: Recall group - electron - shell relationship

Elements in the same group have similar outer - shell electron configurations. However, helium is in Group 18 (noble gases), but its outer shell (the first shell) can hold only 2 electrons. Other noble gases (Ne, Ar, Kr, etc.) have 8 electrons in their outermost shell.

Step2: Analyze other options

Bromine is in Group 17 (halogens) and has 7 outer - shell electrons like other halogens. Boron is in Group 13 and has 3 outer - shell electrons like other Group 13 elements. Hydrogen is in Group 1 and has 1 outer - shell electron like other alkali metals (though hydrogen has unique properties).

Answer:

helium (He)