Names and Formulas of Binary Covalent Compounds

Binary covalent compounds are formed by the combination of two elements, usually nonmetals. Several are so familiar, such as ammonia (NH3), methane (CH4), and water (H2O), that we use their common names, but most are named in a systematic way  

The element with the lower group number in the periodic table is the first word in the name the element with the higher group number is the second word. Exception When the compound contains oxygen and any of the halogens chlorine, bromine, and iodine, the halogen is named first.) 

If both elements are in the same group, the one with the higher period number is named first. 

The second element is named with its root and the suffix -ide. 

Covalent compounds have Greek numerical prefixes (see Table 2.6) to indicate the number of atoms of each element in the compound. The first word has a prefix only when more than one atom of the element is present the second word usually has a numerical prefix. 

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There is a tutorial on the textbook s Web site that provides practice converting between names and formulas of binary covalent compounds. 

Determining Names and Formulas of Binary Covalent Compounds... 

We can probably assume that tbe parent who wrote this note meant the child was taken to the doctor for an injection, but who knows Like everyone else, chemists need to be careful about how they use language, and the names and formulas for chemical compounds form the core of the language of chemistry. The purpose of this section is to describe the guidelines for constructing the names for binary covalent compounds, which are pure substances that consist of two nonmetallic elements. The water, H2O, you boil to cook your eggs and the methane, CH4, in natural gas that can he burned to heat the water are examples of binary covalent compounds. 

Now let s go the other way and convert from systematic names to chemical formulas. The first step in writing formulas when given the systematic name of a binary covalent compound is to recognize the name as representing a binary covalent compound. It will have one of the following general forms. 

You have learned that naming covalent compounds follows different sets of rules depending on the composition of the compound. Table 8.5 summarizes the formulas and names of several covalent compounds. Note that an acid, whether a binary acid or an oxyacid, can have a common name in addition to its compound name. 

Name, write the formula, and calculate the molecule (or formula) mass of ionic arxi binary covalent compounds ( 2.8) (SP 2.5-2.14) (EPs 2.55-2.78)... 

Metal -nonmetal compounds and ammonium compounds (containing the NH4 group within a formula) are ionic. Other compounds are covalent, except that acids are ionized, some completely, when dissolved in water. The acids are named with a special system of their own, but pure binary acids can be named similarly to alkali metal-nonmetal compounds. 

In naming the binary compounds of hydrogen in which hydrogen is written first in the formula, name the compound as if hydrogen were an alkali metal (despite the fact that it is not, and that the compound is covalent). For example, HCl is named hydrogen chloride and H2S is named hydrogen sulfide. [These compounds do form ions to a greater or lesser extent when they are dissolved in water. (Section 8.4)]... 

For each of the following pairs of elements, state whether the binary compound they form is likely to be ionic or covalent. Write the empirical formula and name of the compound (a) B and F, (b) K and Br. 

For each of the following pairs of elements, state whether the binary compound they form is likely to be ionic or covalent. Write the empirical formula and name of the compound (a) I and Cl, (h) Mg and F. For each of the following pairs of elements, state whether the binary compound they form is likely to be ionic or covalent. Write the empirical formula and name of the compound (a) B and F, (h) K and Br. 

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