Carbon polyatomic ions

The oxidation numbers show us that we can combine each of the parts, the calcium and the carbonate, in a 1 1 ratio. We do not, however, remove the subscript of 3 that comes with the carbonate polyatomic ion. If we remove that subscript, the ion fails to be a carbonate ion You must never alter the subscripts that are built into these polyatomic ions. 

Most of the common inorganic (no carbon) polyatomic ions have negative charges. The phosphate ion, PO , has an overall negative charge as does the oxalate ion, C20l. ... 

C09-0107. Write Lewis structures and calculate formal charges for the following polyatomic ions (a) bromate (b) nitrite (c) phosphate and (d) hydrogen carbonate. 

C09-0108. Carbon, nitrogen, and oxygen form two different polyatomic ions cyanate ion, NCO, and isocyanate ion, CNO". Write Lewis stmctures for each anion, including near-equivalent resonance structures and indicating formal charges. 

Not all bases contain hydroxide, however. For example, Na2C03 is a base, but its name is sodium carbonate. Baking soda, which has a chemical formula of NaHC03, is also a base. The scientific name for baking soda is sodium hydrogen carbonate (hydrogen carbonate is the name of the polyatomic ion). 

As we end this section, let us reconsider ionic radii briefly. Many ionic compounds contain complex or polyatomic ions. Clearly, it is going to be extremely difficult to measure the radii of ions such as ammonium, NH4, or carbonate, COs, for instance. However, Yatsimirskii has devised a method which determines a value of the radius of a polyatomic ion by applying the Kapustinskii equation to lattice energies determined from thermochemical cycles. Such values are called thermochemical radii, and Table 1.17 lists some values. 

Ionic compounds consist of positive ions (cations) and negative ions (anions) hence, ionic compounds often consist of a metal and nonmetal. The electrostatic attraction between a cation and anion results in an ionic bond that results in compound formation. Binary ionic compounds form from two elements. Sodium chloride (NaCl) and sodium fluoride (NaF) are examples of binary ionic compounds. Three elements can form ternary ionic compounds. Ternary compounds result when polyatomic ions such as carbonate (C032 ), hydroxide (OH-), ammonium (NH4+), form compounds. For example, a calcium ion, Ca2+, combines with the carbonate ion to form the ternary ionic compound calcium carbonate, CaC03. Molecular compounds form discrete molecular units and often consist of a combination of two nonmetals. Compounds such as water (H20), carbon dioxide (C02), and nitric oxide (NO) represent simple binary molecular compounds. Ternary molecular compounds contain three elements. Glucose ( 12 ) is a ternary molecular compound. There are several distinct differences between ionic and molecular compounds, as summarized in Table 1.2. 

FeCl2 or FeCl3 compound. Therefore iron must include a Roman numeral to specify which cation is in the compound. Iron (II) chloride is FeCl2 and iron (III) chloride is FeCl3. Two or more atoms may combine to form a polyatomic ion. Common polyatomic ions are listed in Table 1.3. The names of polyatomic ions may be used directly in compounds that contain them. Hence, NaOH is sodium hydroxide, CaC03 is calcium carbonate, and Ba(N03)2 is barium nitrate. 

In a similar way it is easy to show that a flat molecule or polyatomic ion (such as CO ion, in which all the atoms lie in a plane and the oxygen atoms form an equilateral triangle round the carbon atom) has a higher refractive index when the electric vector lies in the plane of the group of atoms than when it is perpendicular to this plane. 

How these reactions occur will be explored in later chapters. For now, you should understand that the hydronium and carbonate ions are examples of polyatomic ions, which are molecules that carry a net electric charge. Table 6.1 lists some commonly encountered polyatomic ions. 

Compounds containing polyatomic ions follow similar rules. In sodium carbonate, there are two Na+ ions per carbonate ion, so its formula is Na2C03. When a subscript has to be added to a polyatomic ion, the ion is written within parentheses, as in (NH4)2S04, where (NH4)2 means that there are two NH4+ (ammonium) ions for each S042- (sulfate) ion in ammonium sulfate. In each case, the ions combine in such a way that the positive and negative charges cancel all compounds are electrically neutral overall. 

We first met polyatomic ions and oxoanions in Section C. Many of the most important and common polyatomic anions are the oxoanions (Table D.l). If only one oxoanion of an element is common, its name is formed by adding the suffix -ate to the stem of the name of the element, as in the carbonate ion, C032-. Some elements can form two types of... 

The so-called Coulumb explosion technique, in which ions with translational energies in the MeV regions are denuded of electrons by a thin carbon foil, also promises to provide information on structures and on the symmetries of polyatomic ions [325, 326, 327], as has already... 

Some compounds contain ions that are made from more than one atom. These ions are called polyatomic ions. (The prefix poly means many. ) Calcium carbonate, CaC03, which is found in chalk, contains one calcium cation and one polyatomic anion called carbonate, C032-. 

It is important to learn the names and valences of the five most common polyatomic ions nitrate, carbonate, chlorate, sulfate, and phosphate. These ions form many of the chemicals in nature and in common use. While the task seems overwhelming, it may help to learn the "big five" using a mnemonic, or memory aid. You can use the following mnemonic to remember their names, valences, and number of oxygen atoms ... 

Solution The first two ions are single atom anions and are called sulfide and nitride. The next two are binary ionic compounds, calcium fluoride and potassium sulfide. The polyatomic ions hydroxide and sulfate are present in sodium hydroxide and sodium sulfate. Finally, the last two compounds are covalently bonded and are called sulfur trioxide and carbon tetrachloride. 

The first applications of ion mobility methods to obtain structural information of polyatomic ions were on cluster ions, that is carbon [1-5] and silicon [6, 7] cluster ions. In carbon clusters atoms are bound to each other by covalent bonds, leading to structures like chains for small clusters (<10 atoms), rings, polycyclic... 

The mass determination of ionic species (atomic or polyatomic ions) in mass spectrometry is always a comparative measurement, which means the mass of an ionic species is determined with respect to reference masses of elements (or substances) used for mass calibration. The reference mass is thus acquired from the mass unit (m = In = 1/12) of the mass of the neutral carbon isotope (m = 1.66 X 10 kg). A mass calibration is easy to perform in solid-state mass spectrometry if the sample contains carbon (using carbon cluster ions with whole masses, as discussed above). The so-called doublet method was apphed formerly, e.g., ions and doubly charged Mg + forming a doublet at the same nominal mass number 12 were considered, where they are slightly displaced with respect to one another. The doublet method is no longer of relevance in modern inorganic mass spectrometry. Orientation in the mass spectra can be carried out via the matrix, minor and trace elements after mass calibration and by comparing the measured isotopic pattern of elements with theoretical values. 

Smelling salts often have an unstable ionic compoimd made of two polyatomic ions ammonium and carbonate. 

Compounds made up of three or more elements usually do not decompose into those elements. Instead, each compound that consists of a given polyatomic ion will break down in the same way. For example, a metal carbonate, such as CaCOs in limestone, decomposes to form a metal oxide and carbon dioxide. 

You will often encounter compounds that contain polyatomic ions, and you will simply look up the symbols and oxidation numbers from the second group of oxidation numbers. For example, let s write the proper chemical formula for the compound called calcium carbonate. Use Figures 5-2a and 5-2b to find the symbols and oxidation numbers associated with each ion. 

A. (NH4)2COJ—Ammonium, NH4+, with an oxidation number of +1 must combine with the carbonate, C032, in a 2 1 ratio. We need to put the ammonium ion in parentheses, because it is a polyatomic ion, and we need more than one of them. 

Write the chemical symbol for each of the following ions. Classify each as a monatomic or polyatomic ion. Classify each as a cation or an anion, (a) potassium ion (b) sulfate ion (c) copper(II) ion (d) ammonium ion (e) carbonate ion. 

A molecule or polyatomic ion for which two or more Lewis formulas with the same arrangements of atoms can be drawn to describe the bonding is said to exhibit resonance. The three structures above are resonance structures of the carbonate ion. The relationship among them is indicated by the double-headed arrows, <->. This s)mibol does not mean that the ion flips back and forth among these three structures. The true structure can be described as an average, or hybrid, of the three. 

Some polyatomic ions also have nonsystematic names that are often used. For example, fiC03 is often called bicarbonate instead of hydrogen carbonate. You should avoid using this less accepted name, but because many people still use it, you should know it. 

Convert between the names and chemical formulas for common polyatomic ions such as hydroxide, ammonium, acetate, sulfate, nitrate, phosphate, and carbonate. Be sure to check with your instructor to determine which polyatomic ions you will be expected to know for your exams. 

The cyanide polyatomic ion, CN is similar in structure to carbon monoxide, CO. Although they work by different mechanisms, they are both poisons that can disrupt the use of oxygen, O2, in organisms. Draw a reasonable Lewis structure for the cyanide ion. 

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