chemical elements and their compounds - Sciencemadness Dot Org

3Ql ABBREVIATIONS
Square brackets [ ]: (1) in reaction kinetics mean concentrations (usually in
moles per litre); (2) in formulae indicate ions.
et al. = and others (authors).
Greek and Latin numerical prefixes (uni = mono; ter = tri; sexa = hexa, &c.)
are used indifferently; the supposed objection to 'hybrid' words, of which the
first part is derived from Greek and the second from Latin, if it were valid would
require us to say quadrifluoride but tetrachloride, would reject 'metastable',
and would condemn the Church of England for speaking of the Pananglican
Synod. Note that ennea = 9 and dodeca = 12. Symbols like al, hg, mean
atom/valency (al = J Al: hg = | Hg).
In types of formulae A is as a rule put for the central atom and B for the
covalently attached atoms. E is used for alkyls or aryls, X for halogens and
other monovalent radicals (ionized or not), and Am for NH3 and similar amines.
Other abbreviations are AIk = alkyl; Ar = aryl; Me, Et, Pr, Bu, &c. = methyl,
ethyl, propyl, butyl, &c.; = phenyl (O6H5); Bz = benzyl (C6H6 'CH2);
py = pyridine; en orettethylenediamine; Ox = oxalato-group (C2O4); Cy = CN.
A is sometimes used for the monovalent radical of a diketone or keto-ester (as
C6H7O2 from C6H8O2, apetyl acetone).
SOME USEFUL PHYSICAL CONSTANTS
Lengths : 11* = 10~*; 1 fifi = 10~ 7 ; 1 A or A.U. = 10~ 8 cm. 1 X unit for X-rays
= 1/1000 A (strictly 1/1002 A).
Velocity of light, c = 2-99776 X10 10 cm./sec.
Quantum Theory: Energy E =* hv, where v = frequency (vibrations/second) and
h (Planck's constant) = 6-620 xl0~ 27 erg-seconds.
Absolute zero = 0° K. = -273-16° C.
1 calorie = 4-183 X10 7 ergs = 4-183 joules.
1 electron-volt (e.v., energy acquired by an electron in moving through a
potential drop of 1 volt) is equal to 1-691X 10~ 12 erg, or 23-07 k.cals.
per g.-molecule.
1 Faraday = 96,500 coulombs.
Light Quanta
Wave-number = waves per cm. = frequency/c.
Quantum of wave-length 7,000 A (red end of visible) = 40-8 k.cals./g.-mol.: of
wave-length 4,000 A (violet end) =71-4 k.cals./g.-mol.
Electronic
Transition
Oscillational or Vibrational
Rotational , , ,
Factors for Absorption and Emission Spectra
E. volts
1-10
1/10
1/1000
Energy
Htjg.-mol.
23-230 k.cals.
2*3 k.oale.
S3 calf,
Wave-length
1^,350 to
1,235 A
123,500 A
- 12-85 ja
1,888 ^
m 0*1180 em.
Wave
number.
cm."* 1
8,100 tq
81,000
810
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