created by c. ippolito nov. 2006 the periodic table the periodic table objectives: 1. describe the...
TRANSCRIPT
Created by C. Ippolito
Nov. 2006
The Periodic TableThe Periodic TableObjectives:1. describe the origin of the periodic table2. state the periodic law3. explain the relationship between electron configurations and the location of elements in
the periodic table4. describe the nature of periods and groups of elements in the periodic table5. state the definitions of some properties of the elements that exhibit periodicity6. describe the trends of those properties within periods and groups of elements
Created by C. Ippolito
Nov. 2006
Early Classification SystemsEarly Classification Systems 1817 Johann Dobreiner
noticed that Ca, Ba, and Sr possess similar propertiesnoticed that mass of Sr was halfway between Ca and Bacalled this “group” a triad
– found two additional triads Cl, I and Br S, Te, and Se
1863 John Newlandsarranged elements in atomic mass order
– properties repeat every eighth element
Law of Octaves – made seven groups of seven elements each
Created by C. Ippolito
Nov. 2006
Mendeleev’s Periodic TableMendeleev’s Periodic Table
1869 Dmitri Mendeleevproperties were a function of atomic mass
– periods of varying lengths 7, 7, 17– left blank spots so he could put similar
properties in same column predicted properties of “empty” spots when discovered they matched his predictions
Mendeleev’s Periodic Law– the properties of elements repeat in an orderly
fashion as a function of their atomic masses
Created by C. Ippolito
Nov. 2006
Modern Periodic LawModern Periodic Law Mendeleev problems
I and Te – I before Te by mass; I after Te by properties
– put them by properties; thought masses measured incorrectly
– Co and Nickel; K and Ar similar problems Henry Moseley
properties of elements are a periodic function of their atomic numberatomic number not atomic mass
Created by C. Ippolito
Nov. 2006
Reading the Periodic TableReading the Periodic Table Periods
horizontal rows– begin on left with a metalmetal and end on right with noble gasnoble gas
Family or Groupvertical rows
– similar physical and chemical properties– 1 – 2 and 13 – 18
have same number of valence electronsvalence electrons – 3 – 12
s level of outermost energy level has 1 or 2 electrons d levels are “being” filled
Created by C. Ippolito
Nov. 2006
Periods of ElementsPeriods of Elements Period Number
the energy level of its Valence Electrons Short Periods (1, 2 and 3)
elements with up to 2e-, 8e- and 8e-
Period 1 (H and He)– completes 1s level
Period 2 (Li, Be, B, C, N, O, F, and Ne)– begins filling 2nd Level with Ne having 2s and 2p levels completed
Period 3 (Na, Mg, Al, Si, P, S, Cl and Ar)– begins filling 3rd Level with Ar having 3s and 3p levels completed
Created by C. Ippolito
Nov. 2006
Periods of ElementsPeriods of Elements Period Number
the energy level of its Valence Electrons Long Periods (4 and 5)
each contain 18 elementsPeriod 4 (K thru Kr)
– K and Ca are completing 4s level– Sc thru Cu completed 4s and are filling 3d level
these elements are the transitional metals transitional metals or elements elements– Ga thru Kr are completing the 4p level
Period 5 (Rb thru Xe)– Rb and Sr are completing 5s level– Y thru Cd completed 5s and are filling 4d level
these elements are the transitional metals transitional metals or elements elements– In thru Xe are completing the 5p level
Created by C. Ippolito
Nov. 2006
Periods of ElementsPeriods of Elements Period Number
the energy level of its Valence Electrons Long Periods (6 and 7)
each contain 32 elementsPeriod 6 (Cs thru Rn)
– LanthanidesLanthanides adding electrons to 4f level
Period 7 (Fr thru Uuo)– ActinidesActinides
adding electrons to the 5f level
Created by C. Ippolito
Nov. 2006
Groups of ElementsGroups of Elements Group 1 – Alkali Metals
lose 1e- to form +1 ions Group 2 – Alkaline Earth
Metalslose 2e- to form +2 ions
Group 13 – no special namelose 3e- to form +3 ions
Group 14 – no special namelose 4e- to form +4 ionsgain 4e- to form -4 ions
Group 15 – Nitrogen Familygain 3e- to form -3 ions
Group 16 – Oxygen Familygain 2e- to form -2 ions
Group 17 – Halogensgain 1e- to form -1 ions
Group 18 – Noble Gasescomplete valence level
Created by C. Ippolito
Nov. 2006
Periodic Table of ElementsPeriodic Table of Elements
metalsmetals • metalloidsmetalloids • nonmetalsnonmetals
Created by C. Ippolito
Nov. 2006
Review of the Periodic TableReview of the Periodic Table
Metals are on left side; Nonmetals on right side Majority of elements are metals Each period “opens” a new energy level with a
different principal quantum number Each period represents atoms with “larger”
electron clouds
Created by C. Ippolito
Nov. 2006
Periodicity in PropertiesPeriodicity in Properties Properties directly related to the attraction of
positive nucleus for negative electronsCoulombic attractionCoulombic attraction
– depends on both the quantity of chargequantity of charge and distance distance separating chargesseparating charges
Ionization Energy Electronegativity
Number of ElectronsNumber of Electrons Atomic Radius Ionic Radius
Created by C. Ippolito
Nov. 2006
Periodicity of Ionization EnergyPeriodicity of Ionization Energy Ionization EnergyIonization Energy
removes the most loosely held electron from the outer energy level of an atom in the gas phase.
PeriodicityPeriodicityionization energy increasesincreases as atomic number increases (left to right) in a period
– metals have LOW IONIZATION ENERGIESLOW IONIZATION ENERGIES– nonmetals have HIGH IONIZATION ENERGIESHIGH IONIZATION ENERGIES
ionization energy decreasesdecreases as atomic number increases (top to bottom) in a group
– Shielding EffectShielding Effect inner electrons block attraction of nucleus to outer electrons kernel electrons repel valence electrons
Created by C. Ippolito
Nov. 2006
Ionization Energy vs Atomic NumberIonization Energy vs Atomic Number
Created by C. Ippolito
Nov. 2006
Factors affecting Ionization EnergyFactors affecting Ionization Energy
Nuclear ChargeNuclear Chargeincrease in charge increases ionization energy
ShieldingShieldingincrease in shielding decreases ionization energy
RadiusRadiusincrease in radius decreases ionization energy
SublevelSublevelfull or half full levels require additional energy to be removed
Created by C. Ippolito
Nov. 2006
Electron Affinity vs. ElectronegativityElectron Affinity vs. Electronegativity Electron Affinity
ability of an atom’s nucleus to attract additional electrons– as ionization energy electron affinity
metals have LOW electronegativity nonmetal have HIGH electronegativity
Electronegativitycomparative scale relating element’s atoms ability to attract electrons when bondedincreases from left to right in a period; decreases from top to bottom of a family
– high bonds with low, the greater the difference the stronger the bond
Created by C. Ippolito
Nov. 2006
Atomic Radius and PeriodicityAtomic Radius and Periodicity Atomic Radius
closest distance one atom can approach another atomCovalent Radius
– distance from nucleus to valence shell when covalently bonded decreases left to right in a period; increases top to bottom in a family
van der Waals Radius– distance between nuclei of identical unbonded atoms
Ionic Radius– distance from nucleus to valence electrons in a monoatomic ion
no clear pattern in period; increases top to bottom in family