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Pre‐Periodic Table ChemistryPre Periodic Table Chemistry
• No organization of elements.• Difficult to find information• Difficult to find information.• Chemistry didn’t make sense.
Why is the Periodic Table important to us?Why is the Periodic Table important to us?
• The periodic table is the most useful The periodic table is the most useful tool to a chemist.Y i • You get to use it on every test.
• It organizes lots of information about gall the known elements.
THE MODERN PERIODIC TABLETHE MODERN PERIODIC TABLE
• In modern periodic table elements are • In modern periodic table elements are arranged in increasing order of their ATOMIC NUMBERATOMIC NUMBER
• The horizontal rows are called periods.• The vertical columns are called groups.
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The English physicist (1913) HenryMoseley, showed that the atomicMoseley,number is a more fundamental propertyof an element than its atomic massof an element than its atomic mass.
Modern Periodic LawModern Periodic Law
“Th h i l d h i l“The physical and chemicalproperties of the elements are
i di f i f h iperiodic functions of theiratomic number”
1) The atomic number is equal to the1) The atomic number is equal to thenumber of electrons (or protons) in a
t l tneutral atom.2) Electronic configuration really) g ydetermine the physical and chemicalproperties of elements and theirproperties of elements and theircompounds.
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P i d•Periods are the horizontal rows in the periodic table. p
• There are seven periods in modern periodic table.table.
• They are labeled from 1 to 7.
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Period Number of Number elements
1 Shortest period 22 Short period 83 Short period 83 p4 Long period 185 Long period 185 g p6 Longest period 327 Incomplete period ‐‐‐7 Incomplete period
h d b d h1) The period number corresponds to the principal energy shell (n).
2) The atomic sizes of the elements generallydecreases from left to right in a particularperiod (because nuclear charge increases).
3) In a period, ionization enthalpy, electron gain3) p , py, genthalpy, electronegativity of the elementsincreases (because atomic size decreases).( )
GROUPS
Elements in Why??the same group have similar
• They have the same number of
chemical and physical
same number of valence electrons.
physical properties!!
1)There are 18 groups in the modern periodic1)There are 18 groups in the modern periodictable.) All h l i h2) All the elements present in a group havesame general electronic configuration of thetatoms.
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Example: I group elementsExample: I group elementsLi (3) [He] 2S1
Na (11) [Ne] 3S1
K (19) [Ar] 4S1 [NG] nS1K (19) [Ar] 4S1 [NG] nS1
Rb (37) [Kr] 5S1
Cs (55) [Xe] 6S1
F (8 ) [R ] S1Fr (87) [Rn] 7S1
3) The elements in a group are separated 3) g p pby definite gaps of atomic numbers 2 8 8 18 18 322, 8, 8, 18, 18, 32.
Ex: H (1)Li (3)Li (3)Na (11)K (19)Rb (37)Cs (55)Fr (87)
4) The atomic sizes of the elements in a group 4) The atomic sizes of the elements in a group increases due to the increase the number of shellsof shells
5) In a group, ionization enthalpy, electrongain enthalpy electronegativity of thegain enthalpy, electronegativity of theelements decreases (because atomic sizeincreases)increases).
Families in the Periodic Table1) Elements on the periodic table can be
d i f ili b h igrouped into families bases on theirchemical properties.
2) Families have names, Just like yourfamily has a common last namefamily has a common last name.
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3) Elements in each family have similar3) Elements in each family have similarbut not identical properties.)4) All elements in a family have the samenumber of valence electrons.
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ALKALI METALSFirst group elements…. • Hydrogen is not a member, it y gis a non‐metal
• 1 electron in the outer shell• Soft and silvery metals• Very reactive, esp. with y pwater
• Conduct electricityVikasana - CET 2012
ALKALINE EARTH METALS2nd group elements…2 electrons in the 2 electrons in the outer shellWhite and malleableWhite and malleableReactive, but less than Alkali metalsthan Alkali metalsConduct electricity
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TRANSITION ELEMENTSTRANSITION ELEMENTS
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TRANSITION ELEMENTS
Elements in Groups 3 to 12 1) Good conductors of heat and electricity1) Good conductors of heat and electricity.2) The compounds of transition metals are usually brightly colored and are often used to y g ycolour paints.
3) Transition elements have 1 or 2 valence l h h h l h h felectron, which they lose when they form bonds with other atoms.
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BORON FAMILY 13th group elements….BORON FAMILYAtoms in this family have 3 valence electrons.This family includes a This family includes a metalloid (boron), and the rest are non metals.This family includes the most abundant metal in th th’ t the earth’s crust (aluminum).
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CARBON FAMILY 14th Elements…..R• It Contains elementsimportant to life( b ) d(carbon) andcomputers (silicon).
• Carbon is the basis for• Carbon is the basis foran entire branch ofchemistry.chemistry.
• Silicon and Germanium are important psemiconductors.
NITROGEN FAMILY
Elements of 15th group….5 g pNitrogen makes up over ¾of the atmosphere.Nitrogen and phosphorusare both important inliving thingsliving things.The red stuff on the tip ofmatches is phosphorus.p p
HALOGENS • 17th group elements..g p• Very reactive, diatomic, nonmetalsdiatomic, nonmetals
• Always found combined with other combined with other element in nature .U d di i f t t • Used as disinfectants and to strengthen t thteeth.
OXYGEN FAMILYElements in group 16Elements in group 16Oxygen is necessary f i ifor respiration.Many things that stink, contain sulphur (rotten eggs, garlic, etc.)
The Noble Gases • 18th group elements• VERY unreactive, monatomic gasesg
• Used in lighted “neon” signsneon signs
• Have full valence shellshell.
• Helium (He) has l l t i only 2 electrons in
the outer shell.
Rare Earth Elements • Some are d
Rare Earth ElementsRadioactive
• The rare earths are silvery‐white, or gray metals.
• Conduct electricity
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BLOCKSBLOCKS
) The long form of the periodic table has 1) The long form of the periodic table has also been divided into four blocks, k d d f bl kknown as s, p, d and f – blocks.
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BLOCKS
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2) Classification of blocks depending on the type of orbitals in electrons are filled.
Ex: i) Sodium(Na) belongs to S block, because ) ( ) gvalence electron enters into S orbital. 1S2 2S2 2P6 3S1 3ii) Carbon(6), 1S2, 2S2 2P2. It is p‐block elementelementiii) Fe(26), 1S2, 2S2 2P6,3S2 3P6, 4S2, 3d6. It belongs to d blockbelongs to d‐block.
Locating the position of an element in the periodic table
From electronic configuration of the elementFrom electronic configuration of the element,locate its position in the Periodic Table.
Example: nON Example: nOWhere, n – Period number
O ‐ Block O Block N – Group Number
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1) BLOCK : The sub shell (orbital) in which the valence electron is filled indicate blockelectron is filled indicate block.
2) PERIOD NUMBER : The principal quantum number of the valence shell indicate period numberof the valence shell indicate period number.
3)GROUP NUMBER :a)For S block element: Group No = No of nS electronsa)For S block element: Group No.= No. of nS electrons.b)For p‐block elements: Group No.= 10 + No. of nS & nP
electrons.c) For d‐block elements: Group No. = No. of (n‐1)d + nS
electrons.d) F f bl k l G N d) For f‐block elements: Group No. = 3
Example: 1) Li(3) 1S2 2S1p ) (3)I) Block = S II) Period No. = 2 III) G N III) Group No. = 12) Cl(17) 1S2 2S2 2P6 3S2 3P57 3 3I) Block = P II) Period No. = 3III) G N III) Group No. = 10 +2+5 = 17
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3) Ni(28) 1S2 2S2 2P6 3S2 3P6 4S2 3d83) ( ) 3 3 4 3I) Block = d II) Period No. = 4 III) G N 8 III) Group No. = 2 + 8 = 10
4) Ar(36) 1S2 2S2 2P6 3S2 3P6 3d10 4S2 4P64) (3 ) 3 3 3 4 4I) Block = P II) Period No. = 4III) G N 6 8III) Group No. = 10 + 2+6 = 18
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Write your answers Write your answers
E C: 1SE C: 1S22 2S2S22 2P2P66E C: 1SE C: 1S22 2S2S22 2P2P66
Name the block ? Name the block ?
Period Number ?Period Number ?
Group Number ?Group Number ?
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bl kbl kE C: 1SE C: 1S22 2S2S22 2P2P66
ndnd P i d P i d
PP‐‐blockblockE C: 1SE C: 1S22 2S2S22 2P2P66
Name the block ?Name the block ?
10 + 2 + 6 = 1810 + 2 + 6 = 18thth GroupGroup
22ndnd Period Period Period Number ?Period Number ?
10 + 2 + 6 = 1810 + 2 + 6 = 18 GroupGroupGroup Number ?Group Number ?
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Write your answers Write your answers
E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S11
Name the block ? Name the block ? Period Number ?Period Number ?G N b ?G N b ?Group Number?Group Number?
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SS blockblockE C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S11
stst G G 33rdrd PeriodPeriod
SS‐‐blockblockName the block ? Name the block ? Period Number ?Period Number ?G N b ?G N b ? 11stst Group Group Group Number?Group Number?
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Write your answers Write your answers
E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22E C: 1SE C: 1S 2S2S 2P2P 3S3S3P3P66 4S4S2 2 3d3d66
Name the block ? Name the block ?
P i d N b ?P i d N b ?Period Number ?Period Number ?
Group Number?Group Number?
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Group Number?Group Number?
E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22E C: 1SE C: 1S 2S2S 2P2P 3S3S3P3P66 4S4S2 2 3d3d66
dd Bl kBl kName the block ? Name the block ?
P i d N b ?P i d N b ?
dd‐‐BlockBlock
44thth Period Period Period Number ?Period Number ?
Group Number?Group Number?
44thth Period Period
6 + 2 = 86 + 2 = 8thth GroupGroup
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Group Number?Group Number? 6 + 2 86 + 2 8 GroupGroup
Write your answersWrite your answers
E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22
3P3P44
N th bl k ?N th bl k ?Name the block ? Name the block ?
Period Number ?Period Number ?Period Number ?Period Number ?
Group Number?Group Number?
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pp
E C 1SE C 1S22 2S2S22 2P2P66 3S3S22E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22
3P3P44
Name the block ?Name the block ? PP-- BlockBlockName the block ? Name the block ?
Period Number ?Period Number ?
PP BlockBlock
33rdrd Period Period
Group Number?Group Number? 10 + 2 + 4 = 1610 + 2 + 4 = 16thth GroupGroup
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Write your answers Write your answers
E C 1SE C 1S22 2S2S22 2P2P66 3S3S22E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22
3P3P66 4S4S11
Name the block ?Name the block ?Name the block ? Name the block ?
Period Number ?Period Number ?
Group Number?Group Number?
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E C 1SE C 1S22 2S2S22 2P2P66 3S3S22E C: 1SE C: 1S22 2S2S22 2P2P6 6 3S3S22
3P3P66 4S4S11
Name the block ?Name the block ? SS‐‐BlockBlockName the block ? Name the block ?
Period Number ?Period Number ?
SS BlockBlock
44thth Period Period
Group Number?Group Number? 11stst GroupGroup
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