the atom and redox

8/9/2019 The Atom and REDOX

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The Atomand

REDOX

IntroductionMolar MassIonisation

EnergySubshells

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e -

e-

e -

e -

e -

e -

alton (1805)Atoms

Thomson (1897)Electrons Rutherford (1909)

Central Positive NucleusBohr

(1913)Moseley (1913)Chad !"# (193$)

Atomic Structure: Introduction



Atomic Structure: Introduction%rotons and &eutrons in the &u"leus

• tiny but very dense, so makes up

almost all of the mass

'le"trons in hells

Most of the atom is made up of em ty s a"e*

+tom!" &um,er• e!nition" the number of protons in the

nucleus

C1$

.

i#erent atoms contain di#erent numbers of protons and neutrons, theycan be identi!ed by their nuclear symbol $a di#erent letter or pair ofletters for each element%

Mass &um,er• e!nition" the number of protons and neutrons in the

nucleus



Atomic Structure: Introduction/soto es

• e!nition" Atoms &ith the same number of protons $same element%

but &ith di#erent numbers of neutrons• 'ou could also say isotopes are atoms &ith the same atomic number

but di#erent mass numbers• Isotopes of an element react and behave in e(actly the same &ay as

chemical reactions only involve electrons

C1$

. C13

. C1

.)* + - . neutrons ). + - 7 neutrons )/ + - 8 neutrons



Atomic Structure: Introduction/ons

• e!nition" An atom $or group of atoms% that has gained or lostelectrons and therefore carries charge

• Atoms and ions of the same element &ill behave and react verydi#erently, chemical reactions often cause atoms and ions togain0lose electrons

* electrons - neutral * + * electrons - $ !on * + . electrons - 3 !on

2e5.

$. 2e5.

$. 2e5.

$.

$ 3



Atomic Structure: Relative Mass1IPM" 1ureauInternational

des Poids etMesures

At the 1IPM in Paris, 2rance, a sample of carbon3)*isotope is stored as an international standard to

compare the masses of all other substances to45hy &as carbon chosen6

• Easy to obtain a isotopically pure sample• 7nreactive

5e de!ne )u $uni!ed atomic unit% as e(actly )0)*of the mass of a )* C atom4 8he masses of otherisotopes and elements are often compared to thisvalue, &e call these 9relative: masses4

;elative Isotopic Mass"• e!nition" 8he mass of an atom of an !soto e compared &ith one

t&elfth of the mass of an atom of carbon3)*

• ;elative isotopic masses are e<ual to mass numbers, they shouldal&ays be &hole numbers



;elative Atomic Mass A r"• e!nition" 8he &eighted mean mass of an atom of an element

compared &ith one3t&elfth of the mass of an atom of carbon3)*• $abundance ( mass% = $abundance ( mass% = $abun>44

1romine is made up of"?)@ B1r /B@ ) 1r

$?) ( B% = $/B ( )% )DD

- B4B

total abundance- Ar &ith units gmol 3)

Atomic Structure: Relative Mass



Individual Atoms 3 ;elative Atomic Mass Ar

Simple Molecules 3 ;elative Molecular Mass Mr

• Add up the A r of every atom in onemolecule

• E4g4 Ethanol, C * ? F

$)* ( *% = $) ( % = ) - / gmol 3)

Giant Structures 3 ;elative 2ormula Mass Mr

• Add up the A r of every atom in oneformula unit

• E4g4 Magnesium Chloride, MgCl *

*/4. = $* ( .?4?% - B?4. gmol 3)

Atomic Structure: Relative Mass



2irst Ionisation Energy"• e!nition" the amount of energy re<uired to remove a mole of

electrons from a mole of gaseous atoms to make a mole of gaseous)= ions

H$g% e 3 = H =$g%

•

8o understand ionisation energy you !rst need to understand a fe&key terms

)4 Atomic radius " the distance bet&een the centre of the nucleusand the outer electrons

*4 Nuclear charge" the amount of protons in the nucleus

.4 Shielding" the number of inner shells repelling electrons inouter shells

>A F2 8 ESE 8 INGS AJE AN E22EC8 FN>

Nuclear attraction" 8he pull the nucleus e(erts on the outer

tate ym,ol aseous

Atomic Structure: IonisationEnergy .40$ 10 $3 th!n6s



• 2irst ionisation energy increases as you move across the periodictable $along a ro&, or period%

ithium 1oron 2luorine

! (6) ! (6) e - B (6) B (6) e -

2 (6) 2 (6) e -

?*D kKmol 3) D) kKmol 3) ) ) kKmol 3)

5e need to be able to e(plain this trend using the terms atomic radius , nuclear charge , shielding and !nally nuclear attraction

• As you move across the period table the atomic radius of theatoms decreases

• 8he nuclear charge increases

• 8his increases the nuclear attraction on the outer electrons, somore energy is re<uired to remove them

• $Shielding remains the same as all the atoms have the same

Atomic Structure: IonisationEnergy

L L



• 2irst ionisation energy decreases as you move do&n the periodictable $do&n a column, or group%

ithium Potassium Caesium

! (6) ! (6) e - (6) (6) e -

Cs (6) Cs (6) e -

?*D kKmol 3) /)B kKmol 3) . kKmol 3)

5e also need to be able to e(plain this trend using the terms atomic radius , nuclear charge , shielding and !nally nuclear attraction

• As you move do&n the period table the atomic radius of theatoms increases

• Shielding also increases as the atoms have more shells

• 8herefore nuclear attraction on the outer electrons decreases,so less energy is re<uired to remove them>

• >despite the fact that nuclear charge increases


L L



2irst I4E Mg $g% e 3 = Mg = $g%

Second I4E Mg =$g% e 3 = Mg *=

$g%

8hird I4EMg

*=

$g% e3

= Mg.=

$g%

2ourth I4E Mg .=$g% e 3 = Mg /=

$g%

2ifth I4E Mg /=$g% e 3 = Mg ?=

$g%

Si(th I4E Mg ?= $g% e 3 = Mg = $g%

Seventh I4E Mg =$ % e 3 = Mg =

$ %

. kKmol3)

)/?) kKmol 3)

.. kKmol 3)

)D?/) kKmol 3)

,!6 um *

Second Ionisation Energy"• e!nition" the amount of energy re<uired to remove a mole

of electrons from a mole of gaseous )= ions to make amole of gaseous *= ions

Successive Ionisation Energies

8hird Ionisation Energy"• e!nition " the amount of energy re<uired to remove a

mole of electrons from a mole of gaseous *= ions to makea mole of gaseous .= ions




5e can see the big ump more clearly on agraph

E n e r g y

Successive Ionisation Energies of Mg

) st * nd . rd / th ? th

,!6 um *


Mg

)=*=.=

T h e t h ! r d e l e " t r o n ! s

r e m o : e d f r o m a n ! n n e r

s h e l l



Atomic Structure: IonisationEnergy 8he trend in successive ionisation enthalpies can also be e(plained

using the terms atomic radius , nuclear charge , shielding and !nallynuclear attraction

• As each electron is removed there is less repulsion bet&eenelectrons, so the atomic radius gets $slightly% smaller

• 8he nuclear charge remains the same• 8herefore nuclear attraction on the outer electrons

increases, so more energy is re<uired to remove them

• Some ionisation enthalpies result in an electron beingremoved from an inner shell closer to the nucleus &hiche(periences less shielding

•

8herefore nuclear attraction on the outer electrons increasesdramatically, so a lot more energy is re<uired to remove

E( p la in ing t he incre a s ing t re nd

E( p la in ing t he Mu m ps

L L



Atomic Structure: Subshells &Orbitals

8he large peaks andtroughs tie in &ith ourkno&ledge of electronshells>

> so the smaller peaks andtroughs indicated there mayactually be smaller shells &ithin

shells 5e no& call thesesubshells , &hich contain orbitals 4




8he Solar System Model

hell is made up of atomic orbitals

nition" 9 A region of a molecule &hich can hold a pair of electrons &ith opposit

h orbital holds a ma(imum of * electrons

re are / di#erent types of orbital s,p,d and f each &ith their o&n shape

FrbitalsO

• Frbitals are often represented as bo(es, the electrons

they contain as arro&s, each &ith opposite spin




d• 5 d or,!tals makes up a d su,shell•

2ound in shells .=• . rd lo&est energy . rd to be !lled

s• 1 s or,!tal makes up an s su,shell• 2ound in all shells•

o&est energy )st

to be !lled

• 3 or,!tals makes up a su,s• 2ound in shells *=•

*nd

lo&est energy *nd

to be !lle

f • 7 f or,!tals makes up an f su,sh•

2ound in shells /=• / th lo&est energy / th to be !lled



3

$

1 )s

*s

*p

.s

.p

/s

.d

/p

' n e r 6 y

.s . .d .f 5s 5 5d 5f

s d f

3s 3 3d

$s $1s

2illing Frder

• Subshells !ll from the lo&estenergy up&ards

• Each orbital is !lled singlyuntil the subshell is 9half full:,then pairing begins




Atomic Structure: Subshells &OrbitalsE(ample" Chlorine

)s * *s * *p .s * .p ?

E(ample" Iron

)s * *s * *p .s * .p .d /s *

3d !s st!llr!tten

,efore s



sd

f

; y6en 1s $ $s $ $

; !s !n er!od $444

<!t !s !n the ,lo"#<

<and !t=s theth

elementa"ross

Electroniccon!gurations actlike an address formany elements"




E(ample" Chromium

)s * *s * *p .s * .p 3d 5 s 1E(ample" Copper

)s * *s * *p .s * .p 3d 10 s 1

>a:!n6 a half?lled or fully

?lled 3dsu,shell

ma#es Cr andCu more

sta,le


the atom and redox

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