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Chemical formulas are determined by the ions that can form them. Ions are atoms or molecules that have gained or lost electrons, resulting in a positive or negative charge. The ability of ions to form chemical formulas is based on their charges and the need to achieve a neutral overall charge in a compound.

In the United States, the most common ions that form chemical formulas include cations (positive ions) such as sodium (Na+), calcium (Ca2+), and iron (Fe3+), and anions (negative ions) such as chloride (Cl-), sulfate (SO42-), and oxide (O2-). These ions combine in specific ratios to form compounds with stable electron configurations. For example, sodium chloride (NaCl) is formed by the combination of the sodium cation (Na+) and the chloride anion (Cl-), resulting in a 1:1 ratio to achieve a neutral compound.

The reason for this is rooted in the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a full outer shell of eight electrons, similar to the noble gases. When ions combine, they do so in a way that allows each ion to achieve a stable electron configuration. For instance, sodium has one valence electron and tends to lose it to become a Na+ cation, while chlorine has seven valence electrons and tends to gain one to become a Cl

anion. The combination of one Na+ cation and one Cl- anion results in a neutral compound with a stable electron configuration for both ions.

Data from the American Chemical Society (ACS) indicates that the most common ions in chemical formulas are those that can achieve a stable electron configuration. For example, the ACS states that the most common cations are those with a +1, +2, or +3 charge, while the most common anions are those with a -1, -2, or -3 charge. This aligns with the octet rule and the need for ions to combine in ratios that result in a neutral overall charge.

In conclusion, the ions that can form chemical formulas in the United States are those that can achieve a stable electron configuration through the gain, loss, or sharing of electrons. This is based on the octet rule and the need for compounds to have a neutral overall charge. The most common ions include sodium, calcium, iron, chloride, sulfate, and oxide, which combine in specific ratios to form stable compounds.