Final answer:
The ion NO3- has a total of 24 valence electrons, calculated by adding the valence electrons of nitrogen (5) and three oxygen atoms (18) along with the extra electron from the negative charge of the ion.
Step-by-step explanation:
The question is asking to determine the number of valence electrons in the ion NO3−. To calculate this, we need to add the valence electrons from nitrogen and oxygen and take into account the extra electron from the negative charge of the ion. Nitrogen, with an atomic number of 7, has 5 valence electrons, and each oxygen atom, with an atomic number of 8, has 6 valence electrons. Since there are three oxygen atoms, we have:
1 N atom = 5 valence electrons
3 O atoms = 3 × 6 = 18 valence electrons
Add 1 electron for the 1− charge of the ion: 5 + 18 + 1 = 24 valence electrons. Therefore, the ion NO3− has a total of 24 valence electrons.