Compounds Formulas, Names, and Masses

Names and formulas of compounds form the vocabulary of the chemical language. In this discussion, you ll learn the names and formulas of ionic and simple covalent compounds and how to calculate the mass of a unit of a compound from its formula. 

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Formulas, Names, and Masses of Compounds Binary Ionic Compounds... 

Problem Each box contains a representation of a binary compound. Determine its formula, name, and molecular (formula) mass. 

NIST also maintains a website called the NIST Chemistry WebBook (http //webbook. nist.gov), which provides access to a broad array of data compiled under the Standard Reference Data Program. This site allows a search for thermochemical data for more than 7000 organic and small inorganic compounds, reaction thermochemistry data for over 8000 reactions, IR spectra for over 16,000 compounds, mass spectra for over 15,000 compounds, UV/VIS spectra for over 1600 compounds, electronic and vibrational spectra for over 5000 compounds, spectroscopic constants of over 600 diatomic molecules, ion energetics data for over 16,000 compounds, and thermophysical properties data for 74 selected fluids. The site allows general searches by formula, name, CAS registry number, author, and stracture and also a few specialized searches by properties like molar mass and vibrational energies. 

An ionic compound used as a chemical fertilizer has the composition (by mass) 48.46% O, 23.45% P, 21.21% N, 6.87% H. Give the name and chemical formula of the compound and draw Lewis diagrams for the two types of ions that make it up. 

This formula indicates the actual number of atoms of each constituent element which is present in the molecule in question. It is derived from a knowledge of the empirical formula and the relative molecular mass (RMM). For example, ethyne and benzene each have the same empirical formula, namely CH. How-ever, they have different RMMs, namely 26 and 78 respectively. Accordingly, the molecular formula for each compound is C2H2 and C6H6 respectively. Like the empirical formula,... 

Compound Name and Molecular Mass (mass Molar Mass (mass of Molecular Formula of one molecule) 6.02 x 1023 molecules)... 

If you wish to find IR spectra and mass spectra of common compounds, there are two web sites that are very helpful. Entering a name or molecular formula will give isomers from which to choose the desired structure and the IR or MS if available in their database. 

Compound name and location in a 96-well plate are provided in the form of an Excel spreadsheet. The software then accesses the corporate database and retrieves the empirical formula for each compound (Figure 13.2). Expected mass-to-charge ratio miz) values for the [M -+ H]+ or [M — HJ ions are calculated and take into account that the formula may represent a salt form. Sample information along with the list of expected m/z values... 

The electrons of atoms are involved in forming compounds. In ionic bonding, metal atoms transfer electrons to nonmetal atoms, and the resulting charged particles (ions) attract each other into solid arrays. In covalent bonding, nonmetal atoms share electrons and usually form individual molecules. Each compound has a unique name, formula, and mass based on its component elements. 

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. 

Each substance is identified by the usual form of its chemical formula and by its most commonly employed chemical name. In some cases, with in-termetallic compounds in particular, the name corresponds to a list of the chemical elements in the formula. The molar masses (grnol ) are calculated from the relative atomic masses of the elements taking A = 2 for C and are reported at the beginning or end of the first line. 

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