Final answer:
An atom with a valence of 3 may have a total of 13 electrons, as valence refers to the combining power and reflects the number of valence electrons an element has in its outer shell. Elements from group 13, which have 3 valence electrons, illustrate this concept.
Step-by-step explanation:
An atom with a valence of 3 may have a total of 13 electrons. Valence electrons are the electrons in the outermost shell of an atom that can participate in chemical bonding. The term "valence" refers to the combining capacity of an atom. In the specific case of an element from group 13 of the periodic table, such as aluminum, it has 3 valence electrons.
According to the rules, group 13 elements form 3+ ions (Al³+) when they lose all valence electrons, leaving them with 10 electrons from the previous energy levels. Similarly, group 14 elements like carbon have 4 valence electrons, whereas group 16 elements like oxygen have 6 valence electrons.