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