Sodium atom

Figure Bl.8.4. Two of the crystal structures first solved by W L Bragg. On the left is the stnicture of zincblende, ZnS. Each sulphur atom (large grey spheres) is surrounded by four zinc atoms (small black spheres) at the vertices of a regular tetrahedron, and each zinc atom is surrounded by four sulphur atoms. On the right is tire stnicture of sodium chloride. Each chlorine atom (grey spheres) is sunounded by six sodium atoms (black spheres) at the vertices of a regular octahedron, and each sodium atom is sunounded by six chlorine atoms.

Raab E, Prentiss M, Cable A, Chu S and Pritchard D E 1987 Trapping of neutral sodium atoms with radiation pressure Phys.Rev.Lett. 59 2631-4... 

Cable A, Prentiss M and Bigelow N P 1990 Observation of sodium atoms in a magnetio molasses trap loaded by a oontinuous unoooled souroe Opt. Lett. 15 507-9... 

Gould P L, Lett P D, Julienne P S, Phillips W D, Thorsheim H R and Weiner J 1988 Observation of assooiative ionization of ultraoold laser-trapped sodium atoms Phys.Rev.Lett. 60 788-91... 

Davis K B, Mewes M-0, Andrews M R, van Druten N J, Durfee D S, Kurn D M and Ketterle W 1995 Bose-Einstein oondensation in a gas of sodium atoms Phys.Rev.Lett. 75 3969-73... 

Thorsheim H R, Weiner J and Julienne P S 1987 Laser-induoed photoassooiation of ultraoold sodium atoms Phys.Rev.Lett. 58 2420-3... 

Dulieu O, Giusti-Suzor A and Masnou-Seeuws F 1991 Theoretioal treatment of the assooiative ionization reaotion between two laser-exoited sodium atoms. Direot and indireot processes J.Phys.B At.Moi.Opt.Phys. 24 4391-408... 

The alkali metals have the interesting property of dissolving in some non-aqueous solvents, notably liquid ammonia, to give clear coloured solutions which are excellent reducing agents and are often used as such in organic chemistry. Sodium (for example) forms an intensely blue solution in liquid ammonia and here the outer (3s) electron of each sodium atom is believed to become associated with the solvent ammonia in some way, i.e. the system is Na (solvent) + e" (sohem). 

Upon prolonged standing or, more rapidly, upon refluxing for 4-18 hours, the sodium atom migrates and benzyl-sodium is formed, as is proved by the production of phenylacetic acid in good yield upon carbonation. 

The third period begins with sodium and ends with argon The atomic number Z of sodium is 11 and so a sodium atom has 11 electrons The maximum number of electrons in the Is 2s and 2p orbitals is ten and so the eleventh electron of sodium occupies a 3s orbital The electron configuration of sodium IS 2s 2p 2p 2p is ... 

Transfer of an electron from a sodium atom to a chlorine atom yields a sodium cation and a chloride anion both of which have a noble gas electron configuration... 

In 1817, Josef Fraunhofer (1787-1826) studied the spectrum of solar radiation, observing a continuous spectrum with numerous dark lines. Fraunhofer labeled the most prominent of the dark lines with letters. In 1859, Gustav Kirchhoff (1824-1887) showed that the D line in the solar spectrum was due to the absorption of solar radiation by sodium atoms. The wavelength of the sodium D line is 589 nm. What are the frequency and the wavenumber for this line ... 

The color of the emitted light depends on what type of gas is present. For example, sodium atoms glow with a yellow light (as in the familiar yellow street lights), and neon glow with a dark red light (as in the familiar neon lights). 

In the sodium atom pairs of 3/2 states result from the promotion of the 3s valence electron to any np orbital with n > 2. It is convenient to label the states with this value of n, as n P 1/2 and n f 3/2, the n label being helpful for states that arise when only one electron is promoted and the unpromoted electrons are either in filled orbitals or in an x orbital. The n label can be used, therefore, for hydrogen, the alkali metals, helium and the alkaline earths. In other atoms it is usual to precede the state symbols by the configuration of the electrons in unfilled orbitals, as in the 2p3p state of carbon. 

Figure 9.42 Intensity of sodium atom fluorescence as a function of time following excitation of Nal to the V potential with a pump wavelength of 307 nm (pulse duration ca 50 fs) and a probe wavelength of (a) 575 nm, (b) 580 nm, (c) 589 nm, and (d) 615 nm. (Reproduced, with permission, from Rose, T. S., Rosker, M. J. and Zewail, A. H., J. Chem. Phys., 91, 7415, 1989)...

Optical trapping can also be used as a hthographic tool (90). For example, a combination of optical molasses and an optical standing wave have been used to focus a beam of neutral sodium atoms and deposit them in the desired pattern on a suitable substrate (eg, siUcon). Pattern resolutions of the order of 40 nm with good contrast (up to 10 1 between the intended features and the surrounding unpattemed areas) and deposition rates of about 20 nm /min were obtained (90). 

Intense sodium D-line emission results from excited sodium atoms produced in a highly exothermic step (175). Many gas-phase reactions of the alkafl metals are chemiluminescent, in part because their low ioni2ation potentials favor electron transfer to produce intermediate charge-transfer complexes such as [Ck Na 2] (1 )- There appears to be an analogy with solution-phase electron-transfer chemiluminescence in such reactions. 

A study of interaction of sodium atoms with vibrationaHy excited nitrogen molecules at the intersection of two gas beams shows that conversion of vibrational energy to electronic excitation is substantially more efficient than conversion of translational energy (179). This has also been indicated in other reactions (180). 

Let us start with the sodium atom. It has a nucleus of 11 protons, each with a + charge (and 12 neutrons with no charge at all) surrounded by 11 electrons each carrying a -charge (Fig. 4.3). 

The electrons are attracted to the nucleus by electrostatic forces and therefore have negative energies. But the energies of the electrons are not all the same. Those furthest from the nucleus naturally have the highest (least negative) energy. The electron that we can most easily remove from the sodium atom is therefore the outermost one we... 

Fig. 4.3. The formation of an ionic bond - in this case between a sodium atom and a chlorine atom, making sodium chloride.

The archetype of the ionic ceramic is sodium chloride ("rocksalt"), NaCl, shown in Fig. 16.1(a). Each sodium atom loses an electron to a chlorine atom it is the electrostatic attraction between the Na ions and the CF ions that holds the crystal together. To achieve the maximum electrostatic interaction, each Na has 6 CF neighbours and no Na neighbours (and vice versa) there is no way of arranging single-charged ions that does better than this. So most of the simple ionic ceramics with the formula AB have the rocksalt structure. 

Ethylmalonic Acid.—Like acetoacetic ester (see p. 83), diethylmalonate contains the gioup CO.CHj.CO. By the action of sodium or sodium alroholate, the hydrogen atoms of the methylene group are successively replaceable by sodium. The sodium atoms are in turn replaceable by alkyl or acyl groups. Thus, in the present preparation, ethyl malonic ester is obtained by the action of ethyl iodide on the monosodium compound. If this substance be treated with a second molecule of sodium alcoholate and a second molecule of alkyl iodide, a second radical would be in roduced, and a compound formed of the general formula... 

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