In the context of the periodic table, elements in the same group typically have the same number of electrons in their outermost shell, which contributes to their similar chemical properties.
In this case, the element that does not have the same number of electrons in its outermost shell as the others is hydrogen (H).
- Hydrogen has 1 electron in its outer shell.
- Boron (B) has 3 electrons.
- Bromine (Br) has 7 electrons.
- Helium (He) has 2 electrons.
Thus, hydrogen is the outlier.