Give the number of protons and electrons in each of the following common ions: \(\mathrm{Na}^{+}, \mathrm{Ca}^{2+}, \mathrm{Al}^{3+}, \mathrm{Fe}^{2+}\) \(\mathrm{I}^{-}, \mathrm{F}^{-}, \mathrm{S}^{2-}, \mathrm{O}^{2-},\) and \(\mathrm{N}^{3-}\)

The atomic number is a fundamental part of understanding elements and their ions. This number, typically found above the elemental symbol on the periodic table, indicates the number of protons present in the nucleus of an atom. It's also important to note that in a neutral atom, the number of protons is equal to the number of electrons, which ensures the electrical neutrality of the atom.

For instance, when we look at Sodium (Na), its atomic number is 11. This means every atom of Sodium has 11 protons in its nucleus. If an atom has 11 protons, it will also have 11 electrons when it is not an ion. The atomic number is like an identity, unique to each element, and does not change—even when the atom forms an ion.

When atoms become ions, they either lose or gain electrons to achieve a more stable electronic configuration. But despite this change in electrons, the number of protons—determined by the atomic number—remains unchanged. This constant feature aids in identifying the element. For example, a Sodium ion (Na+) still has 11 protons, the characteristic number for Sodium.

Now consider the Sodium ion's charge of +1; this indicates that it has lost 1 electron. Therefore, this ion has 10 electrons. On the contrary, if an atom forms a negatively charged ion (anion), it has gained electrons. For example, a Sulfur ion (S2-) represents a Sulfur atom that has gained 2 electrons. As Sulfur has an atomic number of 16, the ion will have 16 protons and 18 electrons.

The periodic table is an organized chart of elements arranged by increasing atomic number. Elements in the same column, or group, generally have similar chemical properties and the same number of electrons in their outermost shell, which is significant in ion formation. Groups and periods (the horizontal rows) provide valuable information about the elements' characteristics and how they will interact.

For example, the elements in Group 1, which includes Sodium (Na), are known to form +1 ions due to their tendency to lose a single outer-shell electron. The elements in Group 17 like Fluorine (F) tend to gain one electron, resulting in a -1 charge on the ion. Understanding the layout and information enclosed in the periodic table can help you predict ion formation and charges quite efficiently.

Ions are atoms or molecules that have lost or gained electrons, giving them an electric charge. Positively charged ions are cations, while negatively charged ones are anions. The charge of an ion is crucial as it determines the ion's ability to bond and interact with other ions or molecules.

Let's take two examples: Calcium (Ca) commonly forms a cation with a +2 charge (Ca2+). This indicates that a Calcium atom has lost 2 electrons. On the other hand, the element Chlorine (Cl) often forms an anion with a -1 charge (Cl-), implying it has gained an electron. These charges are not arbitrary but are related to the elements' positions in the periodic table and their electron configurations. By understanding this concept, predicting the formula for the compound that different ions will form becomes much simpler.