Final answer:
The hydronium ion (H3O+) has a total of 1) 8 valence electrons. This is calculated by adding the 6 valence electrons of oxygen with the 3 valence electrons from the three hydrogen atoms and then subtracting one electron due to the positive charge of the ion.
Step-by-step explanation:
The number of valence electrons in a hydronium ion can be determined by counting the valence electrons of the constituent atoms and accounting for the charge of the ion. A hydronium ion is composed of one oxygen atom and three hydrogen atoms with a positive charge (H3O+).
Oxygen belongs to group 16 and has 6 valence electrons. Each hydrogen atom, from group 1, has 1 valence electron. Therefore, the oxygen atom contributes 6 valence electrons and the three hydrogen atoms contribute 1 valence electron each, totaling 3 valence electrons from hydrogen.
The sum of the valence electrons would typically be 6 (from oxygen) + 3 (from hydrogen) = 9. However, since the hydronium ion carries a positive charge, we subtract one electron from this total. Therefore, hydronium ion has a total of 8 valence electrons.