The third shell usually holds eight electrons as well, but can hold up to eighteen in specific circumstances. The number of electrons in the outermost shell of an atom is the same as its group number. In other words, hydrogen has one electron in its outer shell and is in Group I, carbon has four electrons in its outer shell and is in Group IV, and so on. Elements with the same number of electrons in their outer shell have similar chemical properties. Isotopes Neutral elements always have the same number of protons and electrons. However, they can have differing numbers of neutrons, so some atoms of a particular element may be heavier than other atoms of the same
The third shell usually holds eight electrons as well, but can hold up to eighteen in specific circumstances. The number of electrons in the outermost shell of an atom is the same as its group number. In other words, hydrogen has one electron in its outer shell and is in Group I, carbon has four electrons in its outer shell and is in Group IV, and so on. Elements with the same number of electrons in their outer shell have similar chemical properties. Isotopes Neutral elements always have the same number of protons and electrons. However, they can have differing numbers of neutrons, so some atoms of a particular element may be heavier than other atoms of the same