## Chemistry (4th Edition)

For Na$^{+}$, we have 9 protons and 10 electrons. For Ca$^{2+}$, we have 20 protons and 18 electrons. For Al$^{3+}$, we have 13 protons and 10 electrons. For Fe$^{2+}$, we have 26 protons and 24 electrons. For I$^{-}$, we have 9 protons and 10 electrons. For S$^{2-}$, we have 16 protons and 18 electrons. For O$^{2-}$, we have 8 protons and 10 electrons. For N$^{3-}$, we have 7 protons and 10 electrons.
For Na$^{+}$, we first locate the element Na on the periodic table. This element is sodium and has an atomic number of 11. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have a cation with one extra positive charge; therefore, because the number of protons cannot be changed, then the number of electrons must be changed. We have one fewer electron than in a neutral atom, so we have 10 electrons. For Ca$^{2+}$, we first locate the element Ca on the periodic table. This element is calcium and has an atomic number of 20. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have a cation with two extra positive charges; therefore, we have two fewer electrons than in a neutral atom, so we have 18 electrons. For Al$^{3+}$, we first locate the element Al on the periodic table. This element is aluminum and has an atomic number of 13. The atomic number of element the also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have a cation with three extra positive charges; therefore, we have three fewer electrons than in a neutral atom, so we have 10 electrons. For Fe$^{2+}$, we first locate the element Fe on the periodic table. This element is iron and has an atomic number of 26. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have a cation with two extra positive charges; therefore, we have two fewer electrons than in a neutral atom, so we have 24 electrons. For I$^{-}$, we first locate the element I on the periodic table. This element is iodine and has an atomic number of 53. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have an anion with one extra negative charge; therefore, we have one more electron than in a neutral atom, so we have 54 electrons. For F$^{-}$, we first locate the element F on the periodic table. This element is fluorine and has an atomic number of 9. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have an anion with one extra negative charge; therefore, we have one more electron than in a neutral atom, so we have 10 electrons. For S$^{2-}$, we first locate the element S on the periodic table. This element is sulfur and has an atomic number of 16. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have an anion with two extra negative charges; therefore, we have two more electrons than in a neutral atom, so we have 18 electrons. For O$^{2-}$, we first locate the element O on the periodic table. This element is oxygen and has an atomic number of 8. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have an anion with two extra negative charges; therefore, we have two more electrons than in a neutral atom, so we have 10 electrons. For N$^{3-}$, we first locate the element N on the periodic table. This element is nitrogen and has an atomic number of 7. The atomic number of the element also denotes the number of protons in the nucleus of each atom of the element. If we are talking about a neutral atom with no charge, then the number of protons and the number of electrons are equal. However, in this case, we have an anion with three extra negative charges; therefore, we have three more electrons than in a neutral atom, so we have 10 electrons.