3A 4A 5A 6A 7A. What is the formula (symbol and charge) for monatomic ions of O, N, and Te?

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1 3A 4A 5A 6A 7A 5 B Boron 13 Al Aluminum 31 Ga Gallium 49 In Indium 81 Tl Thallium 6 C Carbon 14 Si Silicon 32 Ge Germanium 5 Sn Tin 82 Pb Lead 7 8 N Nitrogen 15 P Phosphorus 33 As senic 51 Sb Antimony 83 Bi Bismuth O Oxygen 34 Se Selenium 9 F S Sulfur 52 Te Tellurium 84 Po Polonium Fluorine Cl Chlorine 35 Br Bromine 53 I Iodine 85 At Astatine 2 lium 1 Ne Neon gon 36 ypton 54 Xe Xenon 86 Radon Figure 1: Nonmetals of the chart. Open lettered elements do not form oxyanions. Notes About Anions Examine the section of the periodic table to the left. The nonmetals are those to the right of the dark-lined stair case. Nonmetals tend to accept electrons from other atoms and consequently collect a negative charge. Nonmetals when occurring as a monatomic ion are negatively charged (e.g. O ) Negative ions are called anions. The noble gases are the elements in column (or ). These elements are completely non reactive (, Ne, and ) or nearly so (, Xe, ). Noble gases do not form monatomic anions. As a rule, the charge on a monatomic ion can be determined by subtracting the column number for noble gases () from the column number containing the element in question. For example the charge on a selenium (Se) ion is (168 = ). The formula for selenide is Se. Bromine is in column17, thus the charge on an ion of bromine is (178 = ), making the formula for bromide (Br ). NOTE: This same idea works if you subtracted (7A - =). Of course the letter A has to be dropped. What is the formula (symbol and charge) for monatomic ions of O, N, and Te? A group of atoms covalently bonded and possessing a charge is called a polyatomic ion. For example the sulfate ion ( SO 4 ) is made up of a single sulfur atom and 4 oxygen atoms bonded together. This cluster of atoms possesses a charge. Negatively charged polyatomic ions involving oxygen are called oxyanions. Column 8a (or ) contains the noble gases. There are no oxyanions of elements in this column. Fluorine, atomic number 9, does not form any oxyanions either. Finally oxygen with oxygen forms O 2 (oxygen) or O 3 (ozone), but not an oxyanion with itself (of course oxygen does form oxyanions just not with itself). All the elements which do not form oxyanions are shown as open letters in the diagram pictured above. The other nonmetals form oxyanions and in most cases more than one. Let s examine the elements of 6A. Oxygen will not form an oxyanion so start with sulfur. There are two common oxyanions of sulfur, namely, sulfite and sulfate. To understand the difference and see regularities on the periodic table we will need to learn a bit about oxidation numbers. Oxygen is assigned a value (which matches its charge as a monatomic anion). The noble gases do not collect electrons and have an oxidation number of. The halogens found in column 7A have a

2 charge as monatomic ions and so do all the oxyanions involving halogens. The element of 6A all have a charge as monatomic ions and so do all oxyanions found in this column. Earlier the formula for sulfate was given as SO 4. For oxyanions of the nonmetals below the top row (below B, C, N, O, F, Ne) the highest number of oxygen atoms present is 4! For these same nonmetals there is typically another oxyanion with three oxygen atoms present. Consequently, the two oxyanions of sulfur are SO 4 (sulfate) and SO 3 (sulfite). Notice that the charge is the same for both sulfate and sulfite oxyanions as well as the monatomic sulfide (S ) ion. An oxyanion ending in -ite has one less oxygen than the oxyanion ending in -ate. Corollary to this observed regularity is that for nonmetals below the first row, the highest number oxygen atoms present in an oxyanion is 4. Also the charge is determined by subtracting from the column number which the element is located. (NOTE: also by subtracting 8 from the number of the A column.) Write the correct formula (which includes the charge of the ion) for the following monatomic ions and the (polyatomic) oxyanions. Recall that monatomic ions end in -ide. Oxyanions end in -ite or -ate depending on the number of oxygen atoms present. sulfate tellurate arsenite selenide chloride nitride sulfite phosphate tellurite bromide oxide selenate phosphite arsenate silicate The monatomic ions follow the pattern follow the pattern of subtract from the column number in which the element is found. The charge of oxyanions below the B, C, N, O, F, Ne row follow the same pattern as monatomic ions. The charge pattern starts at zero since noble gases do not form oxyanions, then for oxyanions of halogens below fluorine, for oxyanions below oxygen itself, for oxyanions below nitrogen and -4 for silicates just below carbon. Oxyanions of row two of the periodic table depart from this pattern. The maximum number of oxygen atoms for these oxyanions is four! Since there are no oxyanions for fluorine and oxygen, the oxyanion of nitrogen starts with the charge of (even though the monatomic nitrogen ion has the expected charge). This progresses with a charge for carbonate and for borate. Moreover, the maximum number of oxygen atoms for oxyanions of the second row is 3! Like before the nitrite has one less oxygen than the nitrate. Write the correct formula for the following monatomic and polyatomic ions of the first row. carbonate nitride nitrite nitrate borate

3 Elements in column 17 are known as halogens. Monatomic ions of halogen follow the group number - pattern. Earlier we noted that all the nonmetal oxyanions below the second row had the same charge as the monatomic ion of the same column and that 4 oxygens atoms was the maximum number in these oxyanions. In column 7A (17) or the halogens all that is still true. What is different is that there can be up to 4 oxyanions for member of column 7A known collectively as halogens. In chlorine there are 4 oxyanions with a charge of (which is also the charge of the monatomic anion chloride (Cl)). Based on the information presented herein the formula for the oxyanion of Cl with the greatest number of oxygen atoms is. You re right it is ClO 4. Since there 4 oxyanions of chlorine what is the formulas for the other 3 Name the following polyatomic ions A) ClO3 B) ClO4 C) IO4 3A 4A 5A 6A 7A B C N O F Ne As Se Br Write the formula from the following names. A) chlorite B) hypochlorite C) bromite NA -4 * Si P S Cl NA -4* Te I Xe At Figure 2: Chares of monatomic anions are above the charges of oxyanion charges.

4 Putting it together. In each element s box are pictured at the right are two charges. The top charge is the monatomic ion and the lower one is the polyatomic ion. An asterisk indicates unusual or mitigating factors. We won t worry about all that now, just patterns. 3A 4A 5A 6A 7A BO3 3- CO3 NO3 NO2 O F Ne In the diagram at the right are listed some common polyatomic ion as formulas. Some of these will not be found in solution such as hypobromite, bromite, or hypiodite. Others will more likely occur as a chain as in the case of silicates. SiO4 4- PO4 3- PO 3 3- AsO4 3- AsO 3 3- SO4 SO 3 SeO4 SeO 3 ClO4 ClO 3 ClO 2 ClO BrO4 BrO 3 BrO 2 BrO TeO4 TeO 3 IO4 IO 3 IO 2 IO Xe Figure 3: Chart shows both the charge and the number of oxygen atoms for nonmetal oxyanions. Summary of patterns: 1. Noble gases do not form monatomic or oxyatomic ions. 2. All nonmetal monatomic ions have a charge that is equal to the (group # 8). 3. Oxyanions do not exist for noble gases, or the elements oxygen and fluorine. 4. All oxyanions of nonmetals found beneath B, C, N, O, and F of the second row have the same charge as the monatomic ion (group # - ). 5. All oxyanions of nonmetals found beneath B, C, N, O, and F have a maxmimum of 4 oxygen atoms (-ate) and usually a minimum of 3 oxygen atoms (-ite). See summary statement number Oxyanions of the second row have a maximum of 3 oxygen atoms (-ate), and only nitrogen forms an additional oxyanion, nitrite. 7. The charge on oxyanions for N, C, and boron are, and respectively. 8. The halogen group can form oxyanions ranging for one oxygen atom to four oxygen atoms. All ions involving halogens are.

5 Write the formula (which includes the correct charge) for each of the following ions. Try to write the formula by using the pattern found on the periodic table as opposed to referring to Table 3. periodate arsenate carbonate nitrate chlorate tellurate bromate iodate phosphate chlorite sulfite nitrite arsenite phosphite perchlorate sulfide selenate selenide selenite hypochorite nitride phosphide fluoride oxide chloride Write the name from the formula of the ion. IO3 Cl CO3 BrO3 Se SeO4 ClO S N 3- O PO4 3- ClO3 NO2 F SO4 NO3 ClO4 AsO4 3- TeO4 SO3