compounds, it may have a combining value of either +2 or +3. Iron with a value of +2 is called ferrous iron ; iron with a value of +3 is called ferric iron.
- The Prefixes hypo and per. When an element exercising positive polarity has three different combining values, the highest is indicated by an adjective ending in ic, the middle value is indicated by an adjective ending in ous, and the lowest value is indicated by an adjective ending with ous in addition to the prefix hypo, which means below or under. Sulphur, for instance, is sulphuric sulphur when it exercises the algebraic combining number of +6 ; it is sul- phurous when it has the combining number +4; it is hypo- sulphurous when it has the combining number of +2.
<Callout type="important" title="Important Rule">When an element exercising positive polarity has four different combining values, the lowest value is indicated by the prefix hypo and the ending ous, the next higher value is indicated by the ending ous without any prefix, the third value is indicated by an adjective ending in ic without any prefix, and the fourth and highest value is indicated by the ending ic and the prefix per.</Callout>
- But even these devices are not always sufficient. We shall accordingly learn now all the prefixes commonly employed in inorganic chemical nomenclature. They are as follows : (a) Prefixes derived from Greek numerals: Mono or mon, meaning one, single or once. Di or dis, meaning two or twice. Tri or tris, meaning three or thrice. Tetra, meaning four. Penta, meaning five. Hexa, meaning six. Hepta, meaning Seven. Octo, meaning eight. Deca, meaning ten.
(b) Prefixes derived from Latin numerals: Un or uni, meaning one or single. Duo, bi, bin, or bis, meaning two or twice. Ter or tri, meaning three or thrice. Quadri or quadra, meaning four. Quinque or quinqui, meaning five. Sexa or sexi, meaning six. Septi or sept, meaning seven. Octo or octi, meaning eight.
(c) Other prefixes: Hypo, meaning under, lower or below. Sub, meaning under, lower or below. Per, meaning thorough, through or to the full extent. Meta, meaning altered, different, after or beyond. Para, meaning changed, different or altered. Ortho, meaning straight, regular, common, usual or original.
The following illustrations will suffice to render clear the mode of employment of the foregoing prefixes : A monochloride is a chloride containing but one chlorine atom ; a dioxide is an oxide containing two oxygen atoms ; a tri-iodide contains three iodine atoms; a tetroxide contains four oxygen atoms; a pentafluoride contains five fluorine atoms ; a hexachloride contains six chlorine atoms ; a hep- toxide contains seven oxygen atoms.
A bicarbonate contains twice as large a proportion of the carbonate radical 003 as a carbonate contains in proportion to the basic element, as shown by the molecular formulas KHOO3 and K2003, in which K is the basic element. Subsulphate of mercury contains a smaller quantity of the sulphate radical S04 in proportion to the mercury than the sulphate of mercury contains. Subnitrate of bismuth is a name given to OBiN03, containing the N03 only once, while bismuth nitrate is Bi(N03)3.
A thiocarbonate is a carbonate in which the oxygen is in part or wholly replaced by sulphur. A thiosulphate is a sulphate containing a larger proportion of sulphur than is contained in the other sulphates, some or all of the oxygen of the sulphate being replaced by sulphur atoms. Thus, sulphate of calcium is CaS04, while thiosulphate of calcium is OaSS4, and other calcium thiosulphates are CaS03S, CaS02S2, and CaSOS3.
- Meta-compounds. The prefix meta when used in connection with hydroxides and salts has a specific meaning. It signifies a compound formed by the removal of the ele- ments of water from another compound of normal structure. A normal hydroxide or a hydroxide of normal composition contains no hydrogen or oxygen, except the hydrogen and oxygen of its hydroxyl. In other words, it contains an equal number of atoms of hydrogen and oxygen, and every hydrogen atom in such a hydroxide is directly united to an oxygen atom.
Thus, ferrous hydroxide is Fe(OH)2, because ferrous iron is a diad and can therefore hold in combination two groups of hydroxyl, OH. Normal ferric hydroxide is Fe(OH)3, 120 A CORRESPONDENCE COURSE IN PHARMACY because ferric iron is a triad and can accordingly hold in combination three hydroxyl groups.
But OFeOH is a meta- hydroxide formed out of Fe(OH)3 by its dissociation, result- ing in the formation of one molecule of water, H20, and one molecule of the OFeOH, which is all that remains of the Fe(OH)3 when one molecule of water has been split off from it.
Normal sulphuric hydroxide or normal sulphuric acid is, of course, S(OH)6, because sulphuric sulphur is a hexad and can hold six hydroxyl groups. But if one molecule of water be split off from the S(OH)6, we would have (HO)4SO left, which is mono-meta-sulphuric acid, or mono-m eta-sulphuric hydroxide, the prefix mono indicating that only one molecule of water was split off.
But if two molecules of water be split off from S(OH)6 or (HO)6S, which is the same thing, then di-meta-sulphuric hydroxide or di-meta-sulphuric acid is formed, the formula of which is (HO)2S02 or H2S04, which is our common sulphuric acid.
A tri-meta-sulphuric acid containing but one atom of sulphur is impossible, because if three molecules of water be split off from (HO)6S, the remainder would be simply S03, which is not a hydrox- ide nor an acid, but sulphuric oxide. The name orthophosphoric acid means the common or ordinary phosphoric acid. The prefix ortho does not indicate its composition, but the ending ic indicates that the phos- phorus in it has the combining number +5, which is the highest of the three positive algebraic combining numbers possible to phosphorus.
The formula for orthophosphoric acid is H3P04 or (HO)3PO. A normal phosphoric hydroxide is, of course, (HO)5P. Accordingly, it is evident that orthophosphoric acid is a mono-meta-acid, and the name mono-meta-phosphoric acid is sufficient to indicate the structure of the compound or its true molecular formula.
The glacial phosphoric acid commonly called meta-phosphoric acid has the formula HP03, or HOP02. It is therefore a CHEMICAL NOMENCLATURE 121 di-meta-acid or (HO)5P, or H5P05 with two molecules of water split off from it, leaving HP03.
What is commonly called pyrophosphoric acid is a phosphoric acid produced by heating orthophosphoric acid, or a pyrophosphate is obtained by heating the corresponding orthophosphate. The common phosphate of sodium is Na2HP04. It is accord- ingly disodium monohydrogen mono-meta-phosphate.
But the pyrophosphate of sodium is Na4P207. The name pyro- phosphate does not indicate the composition, whereas the explicit technical term sodium tri-meta-di-phosphate at once tells the whole story of its structure, for it tells us that the acidic element in the compound is phosphoric phosphorus.
The term diphosphate tells us that it contains two phos- phorus atoms, and the term tri-meta informs us that it differs by three molecules of water from the normal structure of two molecules of sodium phosphate added together. Two molecules of normal phosphoric hydroxide added together would make the formula H10P2O10.
Three molecules of water split off from that formula would leave H4P207. The sodium salt corresponding to H4P207 is Na4P207.
Borax is a sodium penta-meta-tetra-borate, because it is the sodium salt formed out of a boric acid resulting from the splitting off of five molecules of water from four molecules of normal boric hydroxide. It is called a tetra-borate because it contains four boron atoms.
A borate must, of course, be formed from boric acid, and boric boron has a valence of 3. Normal boric hydroxide is accordingly (HO)3B or H3B03. Four molecules of H3B03 would be H12B4012, and after split- ting off five molecules of water from H12B4012, we would have H2B407 left, which is penta-meta-tetra-boric acid, and the sodium salt of it is accordingly Na2B407.
<Callout type="risk" title="Risk">Hypochlorous fluoride (ClF) can be highly reactive with water or other substances, posing a risk of chemical reactions that could release harmful gases.</Callout>
- From the facts stated in the foregoing paragraphs, the student will see that hypochlorous fluoride would be C1F; hypochlorous oxide must be C120 ; hypochlorous acid must 122 A CORRESPONDENCE COURSE IN PHARMACY be HOC1; potassium hypochlorite is KOOl; and calcium hypochlorite Ca(C10)2. Hypophosphorous oxide must be P20. Hypophosphorous acid may be either HOP or it may be HOPH20, in which the student can readily see that the algebraic combining number of the phosphorus is still +1.
Phosphorous oxide must be P203; phosphorous chloride must be PC13; and phosphorous acid may be either (HO)3P or HP02, or it may be even (HO)2PHO, for in all of these formulas of acids it is clearly seen that the phosphorus atom has an algebraic combining number of +3.
The student can readily see at once that H5P05, H3P04, HP03, and H4P307 must all be different kinds of phosphoric acid, because in every one of them the phos- phorus atom clearly has an algebraic combining value of +5.
Upon examination of the formulas H6S06, H4$05, and H2S04, it is seen that these formulas all represent different kinds of sulphuric acid, the first being normal sulphuric acid or sulphuric hydroxide, the second mono-meta-sulphuric acid, and the third di-meta-sulphuric acid, because in all of them the sulphur atom is seen to have a combining value of +6.
The formula CaH4S06 evidently represents a calcium sulphate derived from normal sulphuric hydroxide. CaH2S05 is a sulphate derived from the mono-meta-sulphuric acid, and CaS04 is calcium di-meta-sulphate.
FeH2S05 is ferrous mono-meta-sulphate, which is common ferrous sul- phate, or green vitriol, minus its water of crystallization. Test Questions 1. What is the meaning of Ag ? 2. Why is the symbol representing lead Pb instead of L ? 3. What is I2 and what is the difference between 21 and I2 ? CHEMICAL NOMENCLATURE 123 4. What is the difference between 4H and 2H2 and H4 ? 5. Which of the following formulas are correct and which are incorrect: (a) HgO; (b) Hg20; (c) HgOa; (d) Hg3; (e)H4; (f)04; (g) H2C12 ? 6. Name the two ions of each of the following : ferrous chloride, ferric chloride, sodium nitrate, potassium hy- droxide, phosphoric acid, ammonium sulphate, ammonium chloride, arsenous oxide, antimonous sulphide, potassium antimonite. 7. Write the molecular formulas of the following named compounds: (a) carbonic acid; (b) sodium carbonate; (c) calcium bromide ; (d) potassium fluoride ; (e) silver iodide , (f) nitrogen iodide; (g) barium sulphide; (h) calcium oxide; (i) sulphide of carbon ; (j) sulphide of trivalent arsenic ; (k) the sulphide of quinquivalent antimony; (l) the hydroxide of boron ; (m) three molecules of the sulphate of trivalent iron; (n) two molecules of aluminum sulphate; (o) seven molecules of magnesium hydroxide; (p) two molecules of bismuth nitrate, containing the bismuth as a triad. 8. In which of the two molecules Bi2(003) 3 and (OBi)2C03 is the bismuth trivalent, and what is the combining value of the bismuth in the other ? 9. Write the empiric formula of H202. 10. Write the empiric formula for H20204. 11. Write the molecular formula for the phosphate of triad iron. 12. Write the molecular formula for barium phosphate. 13. Write the molecular formulas for : (a) hypochlorous acid; (b) chlorous acid; (c) chloric acid; (d) perchloric acid ; (e) sodium bromate; (f) potassium periodate; (g) hyposul- phurous acid; (h) sulphuric acid; (i) sulphurous acid; (j) magnesium sulphite; (k) ferrous sulphate; (l) mercuric sulphate; (m) mercurous sulphate; (n) mercuric oxide; (o) sulphurous oxide; (p) hyponitrous acid; (q) nitrous acid; 124 A CORRESPONDENCE COURSE IN PHARMACY (r) nitric acid ; (s) hypophosphite of magnesium ; (t) ferrous hypophosphite ; (u) ferric hypophosphite; (v) phosphoric oxide; (w) carbonic chloride; (x) ammonium phosphate. 14. What is the difference between sulphuric sulphur, sulphurous sulphur and hyposulphurous sulphur ? 15. What is the difference between nitric nitrogen, nitrous nitrogen and hyponitrous nitrogen ? 16. What is the difference between hypochlorous chlorine, chlorous chlorine, chloric chlorine and perchloric chlorine ? 17. What is the combining value of periodic iodine ? 18. What is the algebraic combining value of phosphoric phosphorus ? 19. What is the highest algebraic combining number possible to carbon, and what is carbon with its highest combining value called ? 20. Give the technical name of 00 and of CQ2 ? of H40. 21. What is the algebraic combining number of the acidic element in: (a) hypophosphorous acid; (b) calcium nitrate; (c) ferric sulphate; (d) ferrous sulphate; (e) sodium periodate ; (f ) potassium chlorate ; (g) potassium antimonite ; (h) sodium arsenate; (i) sodium hyposulphite; (j) sodium tetraborate; (k) pyrophosphate of iron; (l) orthophosphate of iron ; (m) metaphosphate of iron ; (n) any decaborate ? 22. How many different kinds of phosphoric acids are possible, containing only one phosphorus atom ? 23. How many different kinds of sulphuric acids are possible, containing only one sulphur atom? 24. What kind of a meta-acid is H2B407 ? 25. Write the formula for normal nitric hydroxide. 26. Write the formula for nitric mono-meta-hydroxide. 27. Write the formula for nitric di-meta-hydroxide. 28. Write the formula for normal sulphuric hydroxide. 29. Write the formula for carbonic hydroxide of normal composition CHEMICAL NOMENCLATUBE 125 30. Write the formula for mono-meta-carbonic hydroxide, 31. What kind of a carbonate is Oa003 ? 32. What kind of a carbonate would you call CaH2C04? 33. What kind of a carbonate would you call KHC03 ? 34. What kind of a carbonate is K2C03 ? 35. Why are all the compounds just named called carbonates ? 36. What is the difference between a chlorate and a perchlorate, and why are both called chlorates ? 37. What is a thiosulphate and what is a hyposulphite ? 38. Give the formula for thiocarbonic acid of normal structure. 39. What would you call a compound of potassium oxygen and pentad iodine ? 40. What would you call a salt containing carbon as its acidic element? 41. What would you call a salt in which the acidic element is silicon? 42. What would you call a salt in which the acidic element is tetrad sulphur ? 43. What would you call a salt in which antimony with five bonds is the acidic element ? 44. How many bonds does the nitrogen have in a hyponitrite ? 45. How many different numbers of bonds can the nitrogen atom have in nitrates ? 46. How many different numbers of bonds can the arsenic atom have in arsenites ? 47. Write the formula for tri-meta-di-phosphoric acid. 48. Write the formula for di-meta-phosphoric acid. 49. If such a compound existed as penta-meta-tetra- phosphoric acid, what would be its formula ?' 50. How many kinds of ferric hydroxide can exist contain- ing but one iron atom ? 126 A CORRESPONDENCE COURSE IN PHARMACY 51. Write the formula for tri-meta-di-ferric hydroxide. 52. Write the formula for a salt containing hexad chromium as its acidic element. 53. What is the difference between acidic manganic manganese and permanganic manganese ? 54. Write the formula for potassium dichromate and state why it is called a dichromate.
LESSON TEN XV The Relative Intensity of the Chemical Combining Energy of Different Elements 225. Different elements possess widely different degrees of intensity of chemical energy, or tendency to combine with other elements or to attack other substances chemically. Among the strikingly energetic elements are fluorine, chlorine, bromine, phosphorus, potassium and sodium. Oxygen also may be said to show considerable inclination to enter into chemical combination, at least at temperatures somewhat above the common. Among the elements of comparatively indifferent chemical energy under ordinary conditions are carbon, silicon, boron, nitrogen, gold and platinum. Neon, argon, krypton and xenon show no inclination what- ever to enter into chemical combination.
The properties of the element fluorine can be studied only with the greatest difficulty, if at all, because whenever that element is liberated from one of its compounds, it instantly attacks some other substance and forms some new chemical combination by uniting with some element in that other substance. Chlorine and bromine are also strikingly energetic in their chemical action upon other substances. Fluorine, chlorine and bromine decompose water and take the hydrogen away from it, setting the oxygen free. They 127 128 A CORRESPONDENCE COURSE IN PHARMACY also attack metals vigorously by combining with them. Fluorine attacks and decomposes glass. Phosphorus ignites and burns fiercely in oxygen and in chlorine and also combines with great velocity with bromine. It decomposes potassium chlorate with great violence. Potassium and sodium and, in still greater measure, caesium and rubidium, decompose water by combining with the oxygen of the water, or with its hydroxyl, and liberating hydrogen. The alkali metals must be preserved submerged in benzoin or some other liquid hydrocarbon (hydrocarbons contain only carbon and hydrogen), to prevent their instant and violent oxidation or combination with oxygen.
Carbon is so indifferent chemically that diamond, graphite, coal and charcoal remain permanently unaltered in the presence of an abundance of oxygen, except when heated strongly. Crystallized silicon, adamantine boron and nitrogen are even more indifferent than carbon. But silicon and boron immediately ignite in fluorine gas, owing to the intense chemical energy of the latter.
- Elements differing widely from each other in their chemical quality show the greatest inclination to enter into combination with each other. Compounds formed by very energetic positive elements with very energetic negative ele- ments are stable; but compounds formed by elements exhibiting a low degree of intensity of chemical energy are comparatively unstable. The fluorides and chlorides of the alkali metals and alkaline earth metals are very stable compounds, because fluorine and chlorine are the most energetic of the decidedly negative elements and the alkaline earth metals are the most energetic of the decidedly positive elements. But most of the com- pounds formed by nitrogen show a remarkable tendency to decompose, often
Key Takeaways
- Understand the rules for naming chemical compounds and their combining values.
- Recognize how different elements combine with varying intensities, aiding in identifying stable or unstable compounds.
- Learn specific prefixes used to denote different combining states of elements.
Practical Tips
- When dealing with reactive chemicals like hypochlorous fluoride (ClF), always handle them with care and ensure proper ventilation to avoid harmful reactions.
- Use the prefix system for naming compounds accurately, ensuring you understand the algebraic combining values of elements involved.
- Identify stable compounds by recognizing those formed between highly energetic positive and negative elements.
Warnings & Risks
- Be cautious when handling reactive chemicals like fluorine or chlorine, as they can decompose water or attack metals violently.
- Avoid mixing incompatible elements to prevent dangerous chemical reactions that could lead to fires or explosions.
- Understand the combining values of elements before attempting to synthesize compounds, especially in emergency situations.
Modern Application
While the specific nomenclature and some chemical properties described in this chapter are historical, understanding the principles of chemical combination can still be valuable for modern survival preparedness. Knowledge of stable compou