ThePar
ti
cul
ateNat
ureofMat
ter
Thekinet
ict heorycanbeusedasasci enti
ficmodelt oexplainhowt hearrangementof
part
icl
esrelatestot heproper
tiesofthet hreestatesofmat ter.
Chemistr
yisaboutwhat
matteri
slikeandhowi tbehav e,andourexpl anati
onsandpr edi
cti
onsofi t
sbehaviour
.
Whatismat ter?Thiswor disusedt ocoverallthesubstancesandmat eri
alsfr
om which
thephysi
caluni verseiscomposed.Ther earemanymi l
l
ionsofdi ffer
entsubstances
known,andal lofthem canbecat egori
sedassol ids,l
i
quidsorgases
Ki
net
icTheor
yofmat
ter
Thekineti
ctheoryhelpstoexplainthewayinwhichmatt
erbehav es.Theev i
denceis
consi
stentwiththeideathatal
lmat teri
smadeupofti
nyparti
cles.Thi s expl
ainsthe
physi
calpropert
iesofmatteri
nt er
msoft hemov
ementofitsconstituentparti
cles.
The
mainpointsofthetheor
yare:
(i
)Allmat t
erismadeupofti
ny,mov
ingpart
icl
es,inv
isi
bletot
henakedeye.Di
ff
erent
substanceshavedif
fer
entt
ypesofpar
ti
cles(atoms,molecul
esorions)whi
chhav e
dif
fer
entsizes.
(i
i
)Thepart
icl
esmov
eal
lthet
ime.Thehi
ghert
het
emper
atur
e,t
hef
ast
ert
heymov
eon
aver
age.
(
ii
i)Heav
ierpar
ti
cl
esmov
emor
esl
owl
ythanl
i
ght
eronesatagi
vent
emper
atur
e.
Expl
aini
ngt
hest
atesofmat
ter
Sol
i
d
I
nasol idtheparti
clesattr
actoneanot her.Therear eattr
acti
v eforcesbet weent he
parti
cleswhichhol
dt hem cl
osetogether.Thepar ti
cleshaveli
tt
lefreedom ofmov ement
andcanonl yvi
brateaboutaf i
xedposi t
ion.Theyar earr
angedi nar egularmanner ,
whichexpl ai
nswhymanysol idsf or
m cr ystal
s.sol i
d,atagi vent emperature,hasa
defi
nitevolumeandshapewhi chmaybeaf fectedbychangesi ntemper ature.Soli
ds
usuall
yslight
lyi
nsizewhen heat ed(expansion)andusual lydecreasei nsizei fcool
ed
(contr
acti
on).
Li
qui
d
I
nal i
qui
dthepart
icl
esarest
il
lcloset oget
herbutt
heymov earoundi
narandom way
andoft
encoll
i
dewi t
honeanother.Thef or
cesofatt
racti
onbet
weenthepar
ticl
esi
na
l
iqui
dareweakert
hanthosei
nasol id.Part
icl
esint
heliqui
dfor
m ofasubst
ancehave
, mor e energy on av er
age than t he part
icl
es i
nt he soli
df or
m of the same
substance.Decreasei
nsizeifcooled(contr
acti
on)
.Ali
quid,atagi
ventemper
ature,has
afixedvolumeandwi llt
akeupt heshapeofanycontai
nerintowhi
chiti
spoured.Likea
sol
id,aliquid'
svolumeissl
ight
lyaffect
edbychangesintemperat
ure.
.
Gas
Inagast hepar ti
clesarerelati
vel
yf arapart.Theyar efreetomov eany wherewi thi
nt he
containerinwhi chtheyar eheld.Theymov er andoml yatv eryhighv elocit
ies,mor e
rapi
dlyt hanthosei nal i
quid.Theycol l
idewitheachot her,butlessof t
ent haninal iquid,
andt heyal socol l
idewi t
ht hewal l
soft hecont ainer.Theyexer tv i
rt
uall
ynof orcesof
attr
actiononeachot herbecauset heyarerelat i
velyfarapar t
.Suchf orces,howev er,are
verysignifi
cant.Iftheydidnotexi stwecoul dnothav esol i
dsorl i
quids.Agas, atagi ven
temper atur
e, hasneitheradef i
nit
enoradef initev ol
ume.I twillt
akeupt heshapeofany
containerintowhi chitisplacedandwi l
lspr eadoutev enlywi t
hinit.Unl i
ket hoseof
soli
dsandl i
quids,thev olumesofgasesar eaf fectedqui t
emar kedlybychangesi n
temper atur
e.l i
quidsandgases,unl ikesoli
ds,ar er elat
ivelycompr essibl
e.Thi smeans
thattheirvolumecanber educedbyt heapplicationofpr essure.Gasesar emuchmor e
compr essiblethanl i
quids.
Thear
rangementofpar
ti
clesi
nsol
i
ds,
li
qui
dsandgasesi
sshowni
nFi
gur
e1.
Changesofst
ate
Theki
net
ict
heor
ymodelcanbeusedt
oexpl
ainhow asubst
ancechangesf
rom one
ti
cul
ateNat
ureofMat
ter
Thekinet
ict heorycanbeusedasasci enti
ficmodelt oexplainhowt hearrangementof
part
icl
esrelatestot heproper
tiesofthet hreestatesofmat ter.
Chemistr
yisaboutwhat
matteri
slikeandhowi tbehav e,andourexpl anati
onsandpr edi
cti
onsofi t
sbehaviour
.
Whatismat ter?Thiswor disusedt ocoverallthesubstancesandmat eri
alsfr
om which
thephysi
caluni verseiscomposed.Ther earemanymi l
l
ionsofdi ffer
entsubstances
known,andal lofthem canbecat egori
sedassol ids,l
i
quidsorgases
Ki
net
icTheor
yofmat
ter
Thekineti
ctheoryhelpstoexplainthewayinwhichmatt
erbehav es.Theev i
denceis
consi
stentwiththeideathatal
lmat teri
smadeupofti
nyparti
cles.Thi s expl
ainsthe
physi
calpropert
iesofmatteri
nt er
msoft hemov
ementofitsconstituentparti
cles.
The
mainpointsofthetheor
yare:
(i
)Allmat t
erismadeupofti
ny,mov
ingpart
icl
es,inv
isi
bletot
henakedeye.Di
ff
erent
substanceshavedif
fer
entt
ypesofpar
ti
cles(atoms,molecul
esorions)whi
chhav e
dif
fer
entsizes.
(i
i
)Thepart
icl
esmov
eal
lthet
ime.Thehi
ghert
het
emper
atur
e,t
hef
ast
ert
heymov
eon
aver
age.
(
ii
i)Heav
ierpar
ti
cl
esmov
emor
esl
owl
ythanl
i
ght
eronesatagi
vent
emper
atur
e.
Expl
aini
ngt
hest
atesofmat
ter
Sol
i
d
I
nasol idtheparti
clesattr
actoneanot her.Therear eattr
acti
v eforcesbet weent he
parti
cleswhichhol
dt hem cl
osetogether.Thepar ti
cleshaveli
tt
lefreedom ofmov ement
andcanonl yvi
brateaboutaf i
xedposi t
ion.Theyar earr
angedi nar egularmanner ,
whichexpl ai
nswhymanysol idsf or
m cr ystal
s.sol i
d,atagi vent emperature,hasa
defi
nitevolumeandshapewhi chmaybeaf fectedbychangesi ntemper ature.Soli
ds
usuall
yslight
lyi
nsizewhen heat ed(expansion)andusual lydecreasei nsizei fcool
ed
(contr
acti
on).
Li
qui
d
I
nal i
qui
dthepart
icl
esarest
il
lcloset oget
herbutt
heymov earoundi
narandom way
andoft
encoll
i
dewi t
honeanother.Thef or
cesofatt
racti
onbet
weenthepar
ticl
esi
na
l
iqui
dareweakert
hanthosei
nasol id.Part
icl
esint
heliqui
dfor
m ofasubst
ancehave
, mor e energy on av er
age than t he part
icl
es i
nt he soli
df or
m of the same
substance.Decreasei
nsizeifcooled(contr
acti
on)
.Ali
quid,atagi
ventemper
ature,has
afixedvolumeandwi llt
akeupt heshapeofanycontai
nerintowhi
chiti
spoured.Likea
sol
id,aliquid'
svolumeissl
ight
lyaffect
edbychangesintemperat
ure.
.
Gas
Inagast hepar ti
clesarerelati
vel
yf arapart.Theyar efreetomov eany wherewi thi
nt he
containerinwhi chtheyar eheld.Theymov er andoml yatv eryhighv elocit
ies,mor e
rapi
dlyt hanthosei nal i
quid.Theycol l
idewitheachot her,butlessof t
ent haninal iquid,
andt heyal socol l
idewi t
ht hewal l
soft hecont ainer.Theyexer tv i
rt
uall
ynof orcesof
attr
actiononeachot herbecauset heyarerelat i
velyfarapar t
.Suchf orces,howev er,are
verysignifi
cant.Iftheydidnotexi stwecoul dnothav esol i
dsorl i
quids.Agas, atagi ven
temper atur
e, hasneitheradef i
nit
enoradef initev ol
ume.I twillt
akeupt heshapeofany
containerintowhi chitisplacedandwi l
lspr eadoutev enlywi t
hinit.Unl i
ket hoseof
soli
dsandl i
quids,thev olumesofgasesar eaf fectedqui t
emar kedlybychangesi n
temper atur
e.l i
quidsandgases,unl ikesoli
ds,ar er elat
ivelycompr essibl
e.Thi smeans
thattheirvolumecanber educedbyt heapplicationofpr essure.Gasesar emuchmor e
compr essiblethanl i
quids.
Thear
rangementofpar
ti
clesi
nsol
i
ds,
li
qui
dsandgasesi
sshowni
nFi
gur
e1.
Changesofst
ate
Theki
net
ict
heor
ymodelcanbeusedt
oexpl
ainhow asubst
ancechangesf
rom one
