Download Atomic`Structure`

Atomic'Structure'
Number'of'protons'
in'the'nucleus'
Neutral'atoms'have'equal'numbers'of'
protons'and'electrons.''The'electrons'can'
occupy'only'specific'energy'levels,'and'each'
energy'level'can'only'contain'a'set'number'of'
electrons'(2'eF'in'E1,'8'eF'in'E2,'etc.)'''
Chemical'bond'
Chemical'bonds'result'from'any'redistribu4on'of'
electrons'that'leads'to'a'more'stable'
configura4on'between'two'or'more'atoms'
The'most'stable'configura4on'–>'''''''''''''''''''''''''''
a'filled'electron'shell'
No'bonds'–'noble'gases'
Ionic'Bonds'
Chemical'bond'in'which'one'or'more'electrons'from'
one'atom'are'removed'and'aOached'to'another'
atom,'resul4ng'in'posi4ve'and'nega4ve'ions'which'
aOract'each'other'
Ionic'Bonds'
Ionic'Bonds'and'Material'Proper4es'
Ions'typically'form'crystal'structures'that'are'strong'
along'the'direc4on'of'the'bonds,'but'can'be'broken'
easily'if'twisted'or'bent'
Ex:'rock,'china,'glass,'bones,''''''''''''''''''''''''''''''''''''''''''''
egg'shells,'salt'
Metallic'Bond'
Chemical'bond'in'which'electrons'are'redistributed'so'
that'they'are'shared'among'many'atoms'
Metallic'Bonds'and'Material'Proper4es'
Unlike'ionic'crystals,'metals'are'malleable'–'upon'
applica4on'of'a'force,'atoms'can'rearrange'
themselves'into'a'different'shape'
Covalent'Bond'
Chemical'bond'in'which'one'or'more'pairs'of'electrons'
are'shared'by'two'atoms'
Covalent'
Bond'
examples'
Covalent'Bonds'and'Material'Proper4es'
Atoms'in'covalent'materials'are'bound'4ghtly'to'each'
other'in'stable'molecules,'but'those'molecules'are'
generally'not'very'strongly'aOracted'to'other'
molecules'in'the'material'
Covalent'Bonds'of'Carbon'
Carbon’s'outer'shell'
contains'four'electrons'
–>'can'form'covalent'
bonds'with'up'to'four'
atoms'
Covalent'Bonds'of'Carbon'
buckyballs'
nanotube'
Organic'
Chemistry'
a'protein'
'''''''''''''''''''''''DNA'
States'of'MaOer'
States'of'MaOer'
Solid'–'any'collec4on'of'atoms'
or'molecules'that'maintains'a'
fixed'shape'and'volume'
Liquid'–'any'collec4on'of'
atoms'or'molecules'that'
has'no'fixed'shape'but'
maintains'its'volume'
Gas'–'any'collec4on'of'
atoms'or'molecules'
that'takes'the'shape'of'
and'fills'the'volume'
available'in'its'
container'
States'of'MaOer'
Plasma'–'similar'to'a'gas,'but'the'electrons'
are'stripped'from'their'atoms'
Types'of'Solids'
crystal'–'groups'of'atoms'
occur'in'a'regularly'
repea4ng'sequence'
glass'–'no'longFrange'order'
to'the'atomic'structure'
polymer'–'long'and'large'
molecules'made'up'of'
smaller'molecules'in'a'
regular'repea4ng'
sequence'''
Material'Proper4es'F'Strength'
Strength'is'the'ability'of'a'solid'to'resist'changes'in'shape'
Strong'materials'require'strong'chemical'bonds'
Material'Proper4es'F'Strength'
Strength'is'the'ability'of'a'solid'to'resist'changes'in'shape'
Strong'materials'require'strong'chemical'bonds'
Many'strong'materials'–'rocks,'glass,'ceramics'–'are'held'
together'by'ionic'bonds'
Material'Proper4es'F'Strength'
Strength'is'the'ability'of'a'solid'to'resist'changes'in'shape'
Strong'materials'require'strong'chemical'bonds'
The'strongest'materials'we'know'–'spider'webs,'Kevlar,'
diamonds,'plas4cs,'etc.'–'contain'long'chains'and'
clusters'of'carbon'atoms'held'together'by'covalent'
bonds'
Kevlar'
aerogel'
Composite'Materials'
Combina4ons'of'two'or'more'materials,'typically'
designed'so'the'strength'of'one'of'the'materials'
offsets'a'weakness'of'another'
Examples:'
Composite'Materials'
Combina4ons'of'two'or'more'materials,'typically'
designed'so'the'strength'of'one'of'the'materials'
offsets'a'weakness'of'another'
Examples:'plywood,'reinforced'concrete,'car'windshield'
Electrical'Proper4es'of'Materials'
Electrical'Proper4es'of'Materials'
Conductor'–'any'material'capable'of'carrying'electrical'
current'
Insulator'–'a'material'that'will'not'conduct'electricity'
(unless'subjected'to'an'extremely'high'voltage)'
Conductors'
Insulators'
Electrical'Proper4es'of'Materials'
Conductor'–'any'material'capable'of'carrying'electrical'
current'
Insulator'–'a'material'that'will'not'conduct'electricity'
(unless'subjected'to'an'extremely'high'voltage)'
Superconductor'–'a'material'that'conducts'electricity'
without'resistance'
Semiconductor'–'neither'a'good'conductor'nor'perfect'
insulator'
Applica4ons'of'
superconduc4vity'
SiliconFbased'Semiconductors'
Diodes'
A'combina4on'of'one'nFtype'semiconductor'and'one'pF
type'semiconductor''
It'allows'the'flow'of'current'in'only'one'direc4on'
Diodes'
A'combina4on'of'one'nFtype'semiconductor'and'one'pF
type'semiconductor''
It'allows'the'flow'of'current'in'only'one'direc4on'
Transistors'
A'combina4on'of'one'type'of'semiconductor'
sandwiched'in'between'two'semiconductors'of'the'
opposite'type'
p''''''''''''n''''''''''''''p'
n'''''''''''''p''''''''''''''n'
Transistors'
A'combina4on'of'one'type'of'semiconductor'(base)'
sandwiched'in'between'two'semiconductors'of'the'
opposite'type'
A'small'amount'of'electrical'charge'run'into'or'out'of'
the'base'can'change'the'electric'fields'at'each'
junc4on,'thus'controlling'the'current'through'the'
transistor'
Transistors'can'be'used'as'amplifiers'(cell'phone,'radio)'
or'switches'(computers)'
n'''''''''''''p''''''''''''''n'