1 A A t t o o m m i i c c S S t t r r u u c c t t u u r r e e Par Par t 3 t 3
Structure Of Atoms Part 3
May 21, 2015
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AAttoommiic c SSttrruuccttuurree
ParPart 3t 3
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Recap
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Recap
• Isotopes:Atoms of the same element having the same number of protons but different number of neutrons
•Hydrogen has three isotopes and chlorine has two isotopes
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Recap
• The attractive force between the positive charge on the nucleus and the negative charge on the electrons is called electrostatic force
• The way the electrons are arranged is called its electronic structure
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Recap
2nd shell8 electrons
4th shell8 electrons
Nucleus
3rd shell
8 electrons(proton number 20)
1st shell2 electrons
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Recap
To find the To find the electronic configurationelectronic configuration of of an atom, we shouldan atom, we should
(1)(1) Fill the electrons into the shell Fill the electrons into the shell nearest to the nucleus first. This shell nearest to the nucleus first. This shell
can take a maximum of 2 electronscan take a maximum of 2 electrons
(2)(2) Once this shell is filled, the Once this shell is filled, the electrons go to the next available electrons go to the next available shell which has a maximum shell which has a maximum capacity of capacity of 8 electrons, and so on.8 electrons, and so on.
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Overview of topic
Atomic Structure
Structure of Atoms
Isotopes
Electronic Arrangement
Electronic Structure and the Periodic Table
Ions
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Today’s Menu•Outermost electronsOutermost electrons• Electronic structures and Electronic structures and
The Periodic TableThe Periodic Table• Electrons Structures of Electrons Structures of
Noble GasesNoble Gases• IonsIons
- Positively charged (+) ions- Positively charged (+) ions
- Negatively charged (-) ions- Negatively charged (-) ions
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What are What are outermost outermost electronselectrons
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What are outermost What are outermost electronselectrons
Na
The shell furthest The shell furthest away from nucleus away from nucleus is known as the is known as the outermost shelloutermost shell
The electrons on The electrons on the outermost shell the outermost shell are known as the are known as the outermost outermost electronselectrons
Outermost Outermost electrons are also electrons are also known as known as valence valence electronselectrons
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What are outermost What are outermost electronselectrons
Na
• The outermost The outermost electrons electrons take parttake part in chemical in chemical reactionsreactions
• The inner-shell The inner-shell electrons electrons do notdo not take part in take part in chemical reactionchemical reaction
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What are outermost What are outermost electronselectrons
ExampleExample
ElementElement Electronic Electronic ConfiguratiConfigurati
onon
No. of No. of outermosoutermos
t et e-- (Valency)(Valency)
No. of eNo. of e-- taking taking part in part in
chemical chemical reactionsreactions
AluminiAluminiumum
2, 8, 32, 8, 3
CarbonCarbon 2, 42, 4
OxygenOxygen 2, 62, 6
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66
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44
66
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Electronic Electronic Structures & The Structures & The
Periodic TablePeriodic Table
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Electronic Structures & The Periodic Electronic Structures & The Periodic TableTable
• The Periodic Table is a way of The Periodic Table is a way of arranging elements by arranging elements by their their valencyvalency
• Elements with the Elements with the same same number of outermost electronsnumber of outermost electrons are in the are in the same same GroupGroup
• The vertical set of elements in The vertical set of elements in the Periodic Table is called a the Periodic Table is called a GroupGroup
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Electronic Structures & The Periodic Electronic Structures & The Periodic TableTable
GrouGroupp
ExampExamplele
Electronic Electronic ConfigurationConfiguration
ValencValencyy
II LiLi 2,12,1 11
NaNa 2, 8, 12, 8, 1
IIII BeBe 2, 22, 2 22
MgMg 2, 8, 22, 8, 2
IIIIII BB 2 ,32 ,3 33
AlAl 2, 8, 32, 8, 3
IVIV CC 2, 42, 4 44
SiSi 2, 8, 42, 8, 4
VV NN 2, 52, 5 55
PP 2, 8, 52, 8, 5
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Electronic Structures & The Periodic Electronic Structures & The Periodic TableTable
GrouGroupp
ExampExamplele
Electronic Electronic ConfigurationConfiguration
ValencValencyy
VIVI OO 66 66
SS 2, 8, 62, 8, 6
VIIVII FF 2, 72, 7 77
ClCl 2, 8, 72, 8, 7
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Electron Structure of Noble Gases
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Electron Structure of Noble Electron Structure of Noble GasesGases
• Noble gases are in Group Noble gases are in Group 00• They have They have full full outermost shelloutermost shell
He
Electronic Electronic ConfiguratiConfiguration: 2 on: 2 (duplet)(duplet)
Electronic Electronic ConfiguratiConfiguration: 2, 8 on: 2, 8 (octet)(octet)
Ne Ar
Electronic Electronic ConfigurationConfiguration: 2, 8, 8 : 2, 8, 8 (octet)(octet)
ExampleExamples:s:
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Electron Structure of Noble Electron Structure of Noble GasesGases
• Noble gases are unreactive = inert gases
• Noble gases are very stable as they have no tendency to combine with other elements
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Practice Time
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IonsIons
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Ions
•Atoms form ions by Atoms form ions by losing or losing or gaining electronsgaining electrons to achieve to achieve the stable full shell the stable full shell configuration of a noble gasconfiguration of a noble gas
• Ion is a Ion is a chargedcharged particle particle
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Ions
• There are 2 types of ion:There are 2 types of ion:
IonIonss
Positively Positively (+) charged (+) charged ionsions
(Cations)(Cations)
Negatively Negatively (-) charged (-) charged ionsions
(Anions)(Anions)
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Ions
Remember this. . . Remember this. . .
• In an Atom,In an Atom,
No. of = No. of No. of = No. of
• Therefore, an atom is Therefore, an atom is
protonsprotons electronselectrons
electricalelectricallylyneutrneutr
alal
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Positively Charged Ion
• When electrons are When electrons are lostlost from an from an atom, atom, the atom has the atom has moremore protons protons than than electronselectrons
• There is an overall There is an overall positivepositive charge charge
• Hence, a Hence, a positively charged ionpositively charged ion (cation) (cation) is formed is formed
X – eX – e-- X X++
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Negatively Charged Ion
• When electrons are When electrons are gainedgained from an from an atom, the atom has atom, the atom has lessless protons protons than than electronselectrons
• There is an overall There is an overall negativenegative charge charge
• Hence, a Hence, a negatively charged ionnegatively charged ion (anion) (anion) is formed is formed
X + eX + e-- X X--
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Why do atoms lose Why do atoms lose or gain electronsor gain electrons
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Why do atoms lose or gain Why do atoms lose or gain electronselectrons
Atoms lose or gain electrons Atoms lose or gain electrons so as to achieve the stable so as to achieve the stable full shell configuration of a full shell configuration of a noble gas noble gas
i.e. duplet (2 ei.e. duplet (2 e-- in the in the outermost shell) or octet (8 outermost shell) or octet (8 ee-- in the outermost shell) in the outermost shell)
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Practice Time
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SummarSummaryy
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Summary1)1) Electrons found on the Electrons found on the
outermost shells are outermost shells are known as the outermost known as the outermost electron (Valence electron (Valence electrons) electrons)
2) 2) The outermost electrons The outermost electrons take part in chemical take part in chemical reactionsreactions
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Summary
• The Periodic Table is a way The Periodic Table is a way of arranging elements by of arranging elements by their valencytheir valency
• Elements with the same Elements with the same number of outermost number of outermost electrons are in the same electrons are in the same GroupGroup
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Summary• Noble gases are in Group 0Noble gases are in Group 0• They have full outermost shellThey have full outermost shell
He
Electronic Electronic ConfiguratiConfiguration: 2 on: 2 (duplet)(duplet)
Electronic Electronic ConfiguratiConfiguration: 2, 8 on: 2, 8 (octet)(octet)
Ne Ar
Electronic Electronic ConfigurationConfiguration: 2, 8, 8 : 2, 8, 8 (octet)(octet)
ExampleExamples:s:
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Summary
• Atoms form ions by losing or gaining Atoms form ions by losing or gaining electrons to achieve the stable full electrons to achieve the stable full shell configuration of a noble gasshell configuration of a noble gas
•There are 2 types of ion:There are 2 types of ion:
IonIonss
Positively Positively (+) charged (+) charged ionsions
(Cations)(Cations)
Negatively Negatively (-) charged (-) charged ionsions
(Anions)(Anions)
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Summary
• Positively charged ion (cation)Positively charged ion (cation)
• Negatively charged ion (anion)Negatively charged ion (anion)
X – eX – e-- X X++
X + eX + e-- X X--
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Summary
• Atoms lose or gain electrons so Atoms lose or gain electrons so as to achieve the stable full as to achieve the stable full shell configuration of a noble shell configuration of a noble gas gas
i.e. duplet (2 e- in the i.e. duplet (2 e- in the outermost shell) or octet (8 e- outermost shell) or octet (8 e- in the outermost shell)in the outermost shell)
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Any Any QuestionsQuestions
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