Atoms stable

Why is the H atom stable, and what are its allowed energy levels ... 

In streptocyanine dyes both ends of the methine chain are joined directly to nitrogen atoms, and a double enamine structure is thus present. The dyes are extremely susceptible to hydrolysis, particularly if they contain secondary nitrogen atoms. Stable dyes are obtained if the nitrogen is part of a heterocyclic ring system. Streptocyanine dyes are brilliant yellow dyes that dye polyacrylonitrile and acid-modified polyamide fibers with outstanding lightfastness [1],... 

In such cases, with the halogen and hydroxyl linked to different carbon atoms, stable compounds result. As direct action of halogens oxidizes the alcohol to aldehyde or ketone, this new kind of halogen-alcohol must be prepared by a different reaction. When poly-hydroxy alcohols react with halogen acids, e.g.j hydrochloric acid, HCI, or with phos-... 

Magic number" The number of protons and/or neutrons in an atom that tend to make the atom stable (not radioactive). 

If the two nuclei move even closer, the repulsion between the like-charged nuclei and electron clouds will increase, resulting in repulsive forces that exceed attractive forces. Thus the most stable arrangement of atoms exists at the point of maximum attraction. At that point, the two atoms bond covalently and a molecule forms. Fluorine exists as a diatomic molecule because the sharing of one pair of electrons will give both fluorine atoms stable noble gas configurations. Each fluorine atom in the fluorine molecule has one bonding pair of electrons and three lone pairs, which are unshared pairs of electrons. 

Describe the electron arrangement that makes an atom stable. Why is helium stable with a different arrangement ... 

A full outer shell makes an atom stable. 

Atomization Stable compounds such as carbides can be produced, giving low atomization rates (e.g. Mo) vapour phase reactions, especially molecular condensation at the cooler ends of the furnace (e.g. Pb(g) -I- 2NaCl(g) PbCl2(g) -1- 2Na(g)), can result in nonatomic absorption of incident radiation and scattering of incident radiation by particulates (carbon, smoke, salts). The majority of developments since the introduction of ETAAS are concerned with the elimination of these interferences. 

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

All elements of atomic number greater than 83 exhibit radioactive decay K, Rb, Ir and a few other light elements emit p particles. The heavy elements decay through various isotopes until a stable nucleus is reached. Known half-lives range from seconds to 10 years. 

Radioactive elements may often be prepared artificially by bombarding the atoms of ordinary stable elements with, e.g. helium nuclei. See radioactivity, artificial. 

The radical and ions are exceptionally stable due to resonance the free electron or charge is not localized on the methyl carbon atom but is distributed over the benzene rings. 

The three-dimensional synnnetry that is present in the bulk of a crystalline solid is abruptly lost at the surface. In order to minimize the surface energy, the themiodynamically stable surface atomic structures of many materials differ considerably from the structure of the bulk. These materials are still crystalline at the surface, in that one can define a two-dimensional surface unit cell parallel to the surface, but the atomic positions in the unit cell differ from those of the bulk structure. Such a change in the local structure at the surface is called a reconstruction. 

The hydration of more inert ions has been studied by O labelling mass spectrometry. 0-emiched water is used, and an equilibrium between the solvent and the hydration around the central ion is first attained, after which the cation is extracted rapidly and analysed. The method essentially reveals the number of oxygen atoms that exchange slowly on the timescale of the extraction, and has been used to establish the existence of the stable [1 10304] cluster in aqueous solution. 

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