Lithium rubidium sodium

All the cations of Group I produce a characteristic colour in a flame (lithium, red sodium, yellow potassium, violet rubidium, dark red caesium, blue). The test may be applied quantitatively by atomising an aqueous solution containing Group I cations into a flame and determining the intensities of emission over the visible spectrum with a spectrophotometer Jlame photometry). 

Dicaesium acetylide Copper(ll) acetylide Dicopper(l) acetylide Silver acetylide Caesium acetylide Potassium acetylide Lithium acetylide Sodium acetylide Rubidium acetylide Lithium acetylide-ammonia Dipotassium acetylide Dilithium acetylide Disodium acetylide Dirubidium acetylide Strontium acetylide Silver trifluoromethylacetylide Sodium methoxyacetylide Sodium ethoxyacetylide... 

Values of the distance of closest approach derived from experimental values of the activity coefficients are given in column 2 of Table 40. It will be seen that for the lithium and sodium salts the value is greater than the crystal-lattice spacing (given in column 4) by rather more than 1 angstrom, as is expected. For the salts of cesium, rubidium, and potassium, on the other hand, the distance of closest approach... 

Whereas technique (4) works for all alkali metals, lithium and sodium behave differently from potassium, rubidium, and cesium with respect to graphite on direct combination. The last three react facilely with graphite, to form compounds CgM (first stage) and Ci2 M (stage n > 1), but lithium reacts only under more extreme conditions of temperature or pressure, or both, to form compounds of formula CenLi (G3,... 

Sodium hydride ignites in oxygen at 230°C, and finely divided uranium hydride ignites on contact. Lithium hydride, sodium hydride and potassium hydride react slowly in dry air, while rubidium and caesium hydrides ignite. Reaction is accelerated in moist air, and even finely divided lithium hydride ignites then [1], Finely divided magnesium hydride, prepared by pyrolysis, ignites immediately in air [2], See also COMPLEX HYDRIDES... 

Lithium, Li sodium, Na potassium, K rubidium, Rb caesium, Cs francium, Fr... 

Sodium and potassium are among the alkali metals lithium, Li sodium, Na potassium, K rubidium, Rb and cesium, Cs. All these elements are metals and all react with water, explosively, with the exception of lithium. 

All of the alkali metals are electropositive and have an oxidation state of 1 and form cations (positively charged ions) by either giving up or sharing their single valence electron. The other elements of group 1 are lithium (jLi), sodium (jjNa), potassium (j K), rubidium (j Rb), cesium (jjCs), and francium (g Fr). Following are some characteristics of the group 1 alkali metals ... 

They produce distinctive colored flames when burned lithium = crimson sodium = yellow potassium = violet rubidium = purple cesium = blue and the color of francium s flame is not known. Many of francium s characteristics have not been determined owing to the fact that it is rare and all of its many radioactive isotopes have short half-lives. 

Whether the ion pair [(C6H5)2CO 02 "] separates to yield alkali metal superoxide (M02) or collapses to yield alkali metal peroxide (M202) depends upon the stability of the alkali metal superoxide. Thus, in general the yield of superoxide increases as the alkali metal is changed from lithium to sodium to potassium to rubidium, a sequence that parallels the stabilities of the superoxides. Superior yields of superoxides are observed in pyridine solution (Table XI). This is apparently connected with the ability of pyridine to stabilize the superoxide ion by complex formation (25). 

Solvents and potassium ferf-butoxide were purified or prepared as described (18). Rubidium-, sodium-, and lithium ferf-butoxides were prepared by the method described for potassium ferf-butoxide (20). Diphenylmethane (Eastman Kodak Co.) was vacuum-distilled. Fluorene... 

The properties of the alkali metals and of their salts are roughly functions of the at. wt. of the metals. There is generally a break in the curve about potassium so that lithium and sodium form one series, and potassium, rubidium, and caesium another. The properties of the series, K, Rb, Cs generally change more regularly than the series Li, Na, K, although some irregularities do occur—e.g. the m.p. of the nitrates. 

No peritectic point was noticed with lithium chloride and potassium or sodium chlorides. T. W. Richards and W. B. Meldrum (1917) have also studied ternary mixtures of lithium and sodium chlorides with potassium, rubidium, or caesium... 

The solubility of sodium chloride in aq. acetone at 20° falls to 27"18 with 10 c.c. of acetone per 100 c.c. of solvent to 0 25 with 90 c.c. of acetone per 100 c.c. of solvent at 0°, 100 grms. of acetone dissolve 4"6 grms. of lithium chloride, and at 58°, 214 grms., so that the solubility is diminished by a rise of temp. The solubility of potassium in aq. soln. of acetone increases from almost zero with 100 per cent, acetone at 20° to 8"46 with 50 per cent, acetone and to 21 "38 with 20 per cent, acetone. At 30°, 100 grms. of a soln. with 696 per cent, acetone carries 23 42 per cent, potassium chloride and the remainder is water 8"06 per cent, of this salt is present in a soln. with 45 98 per cent, acetone and 0-13 per cent, of this salt in a soln. with 89"88 per cent, of acetone. At 40°, a soln. with 15"75 per cent, acetone carries 21 "28 per cent, of potassium chloride and with 79"34 per cent, of acetone there is 0"58 per cent, of potassium chloride. At 40°, therefore, for cone, of acetone between 20 and 80 per cent., the sat. soln. separates into two layers the upper layer has 55 2 per cent, water, 31 "82 acetone, and 12"99 KC1, when the lower layer has 28"14 per cent, water, 69 42 acetone, and 2"44 KC1. Similarly, when the upper layer has water, acetone, and potassium chloride in the respective ratio 46 49, 45"34, and 8 17 the lower layer has 38 68, 56"17, and 5 25. The separation into two layers with sat. soln. of potassium chloride containing 26 per cent, acetone, occurs at 46"5° and the temp, of separation with other proportions of acetone is indicated in Fig. 22. C. E. Linebarger (1892) and J. E. Snell (1898) 34 found the phenomenon also occurs with the chlorides of lithium, ammonium, sodium, rubidium, calcium, strontium, cobalt, and many other radicles also with bromides, sulphates, cyanides, and numerous other salts with aq. acetone,... 

The sodium salt was prepared similarly. The lithium, rubidium, and cesium salts can also be prepared like this or by using the metal trichlorocobaltatcs14 instead of the trifluorocobaltates. 

Hydrogen, H Lithium, Li Sodium, Na Potassium, K Rubidium, Rb Cesium, Cs Francium, Ft... 

The ability of a metal alcoholate to accommodate an additional molecule of carbohydrate increases with increasing ionic radius " Li < Na < K < Cs. The difference in stoichiometry between lithium and sodium is much greater than that between either sodium and potassium, or potassium and cesium. The coordination number of an alkali metal is known to increase with increasing ionic radius. Brewer148 reported that the maximum number of donor groups oriented about an alkali metal cation is four for lithium, and as many as six for sodium, potassium, rubidium, or cesium. A greater surface area would allow accommodation of more than one carbohydrate moiety but, in addition, solvent molecules are more strongly attached to cations of smaller radius, and these may not be readily displaced by carbohydrate molecules. 

A detailed study of the rearrangement of heptafluoro-2-phenylbut-1-ene (11) to but-2-ene 12 and the E,7. equilibration of 12 showed that lithium and sodium fluorides do not catalyze the rearrangement. Cesium, rubidium, and potassium fluorides are effective catalysts, in that order of decreasing reactivity.25... 

Group 1A—Alkali metals Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) are shiny, soft metals. All react rapidly (often violently) with water to form products that are highly alkaline, or basic—hence the name alkali metals. Because of their high reactivity, the alkali metals are never found in nature in the pure state but only in combination with other elements. 

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