The student is expected to name ionic compounds containing main group or transition metals, covalent compounds, acids, and bases, using International Union of Pure and Applied Chemistry (IUPAC) nomenclature rules AND write the chemical formulas of common polyatomic ions, ionic compounds containing main group or transition metals, covalent compounds, acids, and bases.
Ionic compounds, according to IUPAC nomenclature rules, name the positive ion (cation) first followed by the negative ion (anion). If the anion is monatomic (one atom) the suffix -ide is added to the anion name. If the anion is polyatomic (more than one atom), the name of the complete anion is used without a suffix. The number of electrons lost by the cation must equal the number of electrons gained by the anion to form a neutral ionic compound. Some transition metals have variable charges; therefore a roman numeral is used after the name of the transition metal to indicate the correct charge of the metal cation.
Covalent compounds, according to IUPAC nomenclature rules, are named based on the order that the elements appear in the chemical formula of the compound. The first element is named using a prefix indicating the number of atoms. The second element is named with a prefix indicating the number of atoms, followed by the suffix -ide. In covalent bonds, non-metal atoms share electrons, forming a more stable compound as each atom within the compound achieves a full octet of electrons.
Acids, according to IUPAC nomenclature rules, have a naming convention based on whether the compound is a binary acid or an oxyacid. Binary acids contain hydrogen and a nonmetal. The prefix hydro- is used followed by the root name of the anion and the suffix -ic. Oxyacids (acids that contain hydrogen and a polyatomic ion containing oxygen) use the root name of the anion, and the suffix depends on the number of oxygen atoms in the anion.
Bases, according to the IUPAC nomenclature rules, have a naming convention based on the nature of the base. If the base is an ionic compound, the cation is named first followed by the anion. If the anion is monatomic, the suffix –ide is used. If the anion is polyatomic, the name of the ion is used. If the base is a covalent compound, prefixes are used and the suffix –ide added to the second compound in the formula.
During chemical reactions, elements come together to form different compounds. Scientists represent these compounds by writing chemical formulas. In a chemical formula, the chemical symbols indicate the types of elements that make up a compound, and subscripts represent the quantity of each type of element in ionic or covalent compounds.
IONIC COMPOUNDS
An ionic compound forms when atoms bond by gaining or losing valence electrons. This type of compound usually forms between a metal and a nonmetal. A metal atom donates one or more electrons to a nonmetal. The result is a positively charged ion, called a cation, and a negatively charged ion, called an anion. The cation and anion are joined by an ionic bond. The total number of electrons lost by the cation (or cations) must equal the total number of electrons gained by the anion (or anions) to form a neutral ionic bond.
The Formula Unit
The smallest unit of an ionic compound is called a formula unit. Ionic compounds do not exist as individual molecules. Therefore, a formula unit indicates the lowest reduced ratio of ions in the compound. Balancing the charges in an ionic compound is not always simple. For example, an ionic compound can form between aluminum (Al) and oxygen (O). The aluminum cation has a 3+ charge, and the oxygen anion has a 2- charge. In order for the overall charge to be neutral, two aluminum cations and three oxygen anions must be present in each formula unit for aluminum oxide: Al2O3.
Types of Ionic Compounds
Binary Ionic Compounds: consist of two monoatomic ions, a cation (such as Na+) and an anion (such as Cl- ), forming a salt (NaCl, or table salt).
Polyatomic Ionic Compounds: consist of a monoatomic cation (such as K+) and a polyatomic anion (such as ClO3-) that form a salt (KClO3, or potassium chlorate). Polyatomic ions may also be cations, such as the ammonium ion, NH4+. The majority of polyatomic ions, however, are anions.
Ionic Compounds Nomenclature
Ionic compounds are named according to the International Union of Pure and Applied Chemistry (IUPAC) nomenclature rules. When using this naming system, the positive ion (cation) is listed first, followed by the negative ion (anion). If the anion is monatomic (one atom), the suffix -ide is added to the anion name. If the anion is polyatomic (more than one atom), the name of the complete anion is used without a suffix. The number of electrons lost by the cation must equal the number of electrons gained by the anion in order to form a neutral ionic compound. Some transition metals have variable charges. This means that one type of metal may have a 2+, 3+, and even a 4+ charge. A roman numeral is used after the name of the transition metal to indicate the correct charge of that particular metal cation. For example, one type of iron (Fe) cation may have a 2+ charge. This ion is represented as Fe (II). Another type of iron cation may have a 3+ charge and is represented as Fe (III).
COVALENT COMPOUNDS
A covalent compound forms when atoms bond by sharing electrons. This type of compound usually forms between two or more nonmetal elements. Most nonmetals are found on the upper-right side of the Periodic Table. The exception is hydrogen, which is also a nonmetal and is found in many covalent compounds. Each atom in a covalent compound shares one or more electrons with a neighboring atom, forming a covalent bond. The smallest unit of a covalent compound is called a molecule. In covalent compounds, atoms share electrons to achieve a full octet, or eight valence electrons in its outermost electron shell.
Covalent Compound Nomenclature
Covalent compounds are named according to IUPAC nomenclature rules. When using this naming system, each molecule is named based on the order that the elements appear in the chemical formula of the compound. The first element is named using a prefix indicating the number of atoms of that element. The second element is named with a prefix indicating the number of atoms, followed by the suffix -ide. In covalent bonds, nonmetal atoms share electrons, forming a more stable compound, as each atom within the compound achieves a full octet of electrons.
ACIDS AND BASES
Acids, according to IUPAC nomenclature rules, have a naming convention based on whether the compound is a binary acid or an oxyacid.
Binary acids contain hydrogen and a nonmetal. The prefix hydro- is used, followed by the root name of the anion and the suffix -ic. Oxyacids (acids that contain hydrogen and a polyatomic ion containing oxygen) use the root name of the anion, and the suffix depends on the number of oxygen atoms in the anion.
Bases, according to the IUPAC nomenclature rules, have a naming convention based on the nature of the base.
If the base is an ionic compound, the cation is named first followed by the anion. If the anion is monatomic, the suffix -ide is used. If the anion is polyatomic, the name of the ion is used. If the base is a covalent compound, prefixes are used, and the suffix -ide is added to the second compound in the formula.