Names and Formulas of Ions Formed by One Element

In Section 5.6, elements in the A groups (1, 2, and 13 to 18) of the periodic table were identified as main group elements, and elements in the B groups (3 to 12) were called transition elements. 

The relationship between charges on monoatomic ions and position in the periodic table is explained in Section 11.1. These charges arise when an atom loses or gains one, two, or three electrons to become isoelectronic with a noble-gas atom, that is, when the number and arrangement of electrons is the same as that found in a noble-gas (Croup 8A/18) atom. 

The charged particle formed when an atom gains or loses electrons is an ion. If the ion has a positive charge, it is a cation (pronounced CAT-ion, not ca-SHUN). If the ion has a negative charge, it is an anion (AN-ion). An ion that is formed from a single atom is a monatomic ion. 

The rules for naming monatomic ions depend on where the element is located in the periodic table. The rules for naming ions formed from main group elements are different from the mles for most transition elements. We will first consider how to name ions formed from main group elements. 

The formation of a monatomic ion from an atom can be expressed in a chemical equation. For example, a magnesium atom forms a magnesium ion by losing two electrons  

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Introduction to Nomenclature Formulas of Elements Compounds Made from Two Nonmetals Names and Formulas of Ions Formed by One Element... 

Chemical formulas describe the simplest atom ratio (empirical formula), actual atom number (molecular formula), and atom arrangement (structural formula) of one unit of a compound. An ionic compound is named with cation first and anion second. For metals that can form more than one ion, the charge is shown with a Roman numeral. Oxoanions have suffixes, and sometimes prefixes, attached to the element root name to indicate the number of oxygen atoms. Names of hydrates give the number of associated water molecules with a numerical prefix. Acid names are based on anion names. Covalent compounds have the first word of the name for the element that is leftmost or lower down in the periodic table, and prefixes show the number of each atom. The molecular (or formula) mass of a compound is the sum of the atomic masses in the formula. Molecules are depicted by various types of formulas and models. 

The cations formed as shown by the half-reactions above are simply given the names of the metals that produced them, such as sodium for Na+ and calcium for Ca +. Since they consist of only one element, the name for each anion has an -ide ending, that is, hP", nitride CP , oxide S , sulfide H , hydride F, fluoride and Cl , chloride. An advantage in the nomenclature of ionic compounds is that it is not usually necessary to use prefixes to specify the numbers of each kind of ion in a formula unit. This is because the charges on the ions determine the relative numbers of each, as shown by the examples in Table 4.3. 

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