Fe 音标拼音: [f'e]
铁
铁
Fe n 1 :
a heavy ductile magnetic metallic element ;
is silver -
white in pure form but readily rusts ;
used in construction and tools and armament ;
plays a role in the transport of oxygen by the blood [
synonym : {
iron }, {
Fe }, {
atomic number 26 }]
Ion \
I "
on \ ([
imac ]"[
o ^]
n ),
n . [
Gr . '
io `
n ,
neut ,
of '
iw `
n ,
p .
pr .
of '
ie `
nai to go .]
1 . (
Elec .
Chem .)
an atom or goup of atoms (
radical )
carrying an electrical charge .
It is contrasted with neutral atoms or molecules ,
and free radicals .
Certain compounds ,
such as sodium chloride ,
are composed of complementary ions in the solid (
crystalline )
as well as in solution .
Others ,
notably acids such as hydrogen chloride ,
may occur as neutral molecules in the pure liquid or gas forms ,
and ionize almost completely in dilute aqueous solutions .
In solutions (
as in water )
ions are frequently bound non -
covalently with the molecules of solvent ,
and in that case are said to be solvated .
According to the electrolytic dissociation theory ,
the molecules of electrolytes are divided into ions by water and other solvents .
An ion consists of one or more atoms and carries one unit charges of electricity ,
3 .
4 x 10 ^{-
10 }
electrostatic units ,
or a multiple of this .
Those which are positively electrified (
hydrogen and the metals )
are called {
cations };
negative ions (
hydroxyl and acidic atoms or groups )
are called {
anions }.
Note :
Thus ,
hydrochloric acid ({
HCl })
dissociates ,
in aqueous solution ,
into the hydrogen ion , {
H },
and the chlorine ion , {
Cl -};
ferric nitrate , {
Fe (
NO3 )
3 },
yields the ferric ion , {
Fe },
and nitrate ions , {
NO3 -}, {
NO3 -},
{
NO3 -}.
When a solution containing ions is made part of an electric circuit ,
the cations move toward the cathode ,
the anions toward the anode .
This movement is called migration ,
and the velocity of it differs for different kinds of ions .
If the electromotive force is sufficient ,
electrolysis ensues :
cations give up their charge at the cathode and separate in metallic form or decompose water ,
forming hydrogen and alkali ;
similarly ,
at the anode the element of the anion separates ,
or the metal of the anode is dissolved ,
or decomposition occurs .
Aluminum and chlorine are elements prepared predominantly by such electrolysis ,
and depends on dissolving compounds in a solvent where the element forms ions .
Electrolysis is also used in refining other metals ,
such as copper and silver .
Cf .
{
Anion }, {
Cation }.
[
Webster 1913 Suppl .]
2 .
One of the small electrified particles into which the molecules of a gas are broken up under the action of the electric current ,
of ultraviolet and certain other rays ,
and of high temperatures .
To the properties and behavior of ions the phenomena of the electric discharge through rarefied gases and many other important effects are ascribed .
At low pressures the negative ions appear to be electrons ;
the positive ions ,
atoms minus an electron .
At ordinary pressures each ion seems to include also a number of attached molecules .
Ions may be formed in a gas in various ways .
[
Webster 1913 Suppl .]
Symbol \
Sym "
bol \ (
s [
i ^]
m "
b [
o ^]
l ),
n . [
L .
symbolus ,
symbolum ,
Gr .
sy `
mbolon a sign by which one knows or infers a thing ,
from symba `
llein to throw or put together ,
to compare ;
sy `
n with ba `
llein to throw :
cf .
F .
symbole .
Cf . {
Emblem }, {
Parable }.]
1 .
A visible sign or representation of an idea ;
anything which suggests an idea or quality ,
or another thing ,
as by resemblance or by convention ;
an emblem ;
a representation ;
a type ;
a figure ;
as ,
the lion is the symbol of courage ;
the lamb is the symbol of meekness or patience .
[
1913 Webster ]
A symbol is a sign included in the idea which it represents ,
e .
g .,
an actual part chosen to represent the whole ,
or a lower form or species used as the representative of a higher in the same kind .
--
Coleridge .
[
1913 Webster ]
2 . (
Math .)
Any character used to represent a quantity ,
an operation ,
a relation ,
or an abbreviation .
[
1913 Webster ]
Note :
In crystallography ,
the symbol of a plane is the numerical expression which defines its position relatively to the assumed axes .
[
1913 Webster ]
3 . (
Theol .)
An abstract or compendium of faith or doctrine ;
a creed ,
or a summary of the articles of religion .
[
1913 Webster ]
4 . [
Gr . ?
contributions .]
That which is thrown into a common fund ;
hence ,
an appointed or accustomed duty . [
Obs .]
[
1913 Webster ]
They do their work in the days of peace . . .
and come to pay their symbol in a war or in a plague .
--
Jer .
Taylor .
[
1913 Webster ]
5 .
Share ;
allotment . [
Obs .]
[
1913 Webster ]
The persons who are to be judged . . .
shall all appear to receive their symbol . --
Jer .
Taylor .
[
1913 Webster ]
6 . (
Chem .)
An abbreviation standing for the name of an element and consisting of the initial letter of the Latin or New Latin name ,
or sometimes of the initial letter with a following one ;
as , {
C }
for carbon , {
Na }
for sodium (
Natrium ), {
Fe }
for iron (
Ferrum ), {
Sn }
for tin (
Stannum ),
{
Sb }
for antimony (
Stibium ),
etc .
See the list of names and symbols under {
Element }.
[
1913 Webster ]
Note :
In pure and organic chemistry there are symbols not only for the elements ,
but also for their grouping in formulas ,
radicals ,
or residues ,
as evidenced by their composition ,
reactions ,
synthesis ,
etc .
See the diagram of {
Benzene nucleus },
under {
Benzene }.
[
1913 Webster ]
Syn :
Emblem ;
figure ;
type .
See {
Emblem }.
[
1913 Webster ]
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