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The hydrogen in ammonia is susceptible to replacement by a myriad substituents. Ammonia gas reacts with metallic sodium to give sodamide, NaNH 2. [38] With chlorine, monochloramine is formed. Pentavalent ammonia is known as λ 5-amine, nitrogen pentahydride decomposes spontaneously into trivalent ammonia (λ 3-amine) and hydrogen gas at normal ...
[16] [17] [18] A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that ...
The abbreviation is not always a short form of the word used in the clue. For example: "Knight" for N (the symbol used in chess notation) Taking this one stage further, the clue word can hint at the word or words to be abbreviated rather than giving the word itself. For example: "About" for C or CA (for "circa"), or RE.
2 (right), is formed by a covalent bond when two single hydrogen atoms share two electrons between them. critical point The end point of a phase equilibrium curve or pressure - temperature curve at which conditions are such that phase boundaries vanish and a substance's different phases, such as liquid and vapor , can coexist.
Bifurcated H-bond systems are common in alpha-helical transmembrane proteins between the backbone amide C=O of residue i as the H-bond acceptor and two H-bond donors from residue i + 4: the backbone amide N−H and a side-chain hydroxyl or thiol H +. The energy preference of the bifurcated H-bond hydroxyl or thiol system is -3.4 kcal/mol or -2. ...
Typically these have a metal, such as a copper ion, in the center and a nonmetals atom, such as the nitrogen in an ammonia molecule or oxygen in water in a water molecule, forms a dative bond to the metal center, e.g. tetraamminecopper(II) sulfate [Cu(NH 3) 4]SO 4 ·H 2 O. The metal is known as a "metal center" and the substance that ...
Solid argon-hydrogen clathrate (Ar(H 2) 2) has the same crystal structure as the MgZn 2 Laves phase. It forms at pressures between 4.3 and 220 GPa, though Raman measurements suggest that the H 2 molecules in Ar(H 2) 2 dissociate above 175 GPa. A similar Kr(H 2) 4 solid forms at pressures above 5 GPa. It has a face-centered cubic structure where ...
An American-style 15×15 crossword grid layout. A crossword (or crossword puzzle) is a word game consisting of a grid of black and white squares, into which solvers enter words or phrases ("entries") crossing each other horizontally ("across") and vertically ("down") according to a set of clues. Each white square is typically filled with one ...