CP ChemistryCP Chemistry

Chapter 11 Chapter 11 Patterns in the Periodic TablePatterns in the Periodic Table

Development of Periodic Development of Periodic TableTable

• 1800 – scientists began to see 1800 – scientists began to see patterns in properties of elementspatterns in properties of elements

• 18291829• Dobereiner – German chemist – first Dobereiner – German chemist – first

periodic tableperiodic table• Put elements with similar properties Put elements with similar properties

in groups of three – called “triads”in groups of three – called “triads”

• Example of one of his triads: Example of one of his triads: chlorinechlorine, , brominebromine, , iodineiodine

• Did not work so well with the other Did not work so well with the other elements known at that timeelements known at that time

• 1864 Newlands1864 Newlands• Suggested that elements could be Suggested that elements could be

put in groups of eight – “octaves”put in groups of eight – “octaves”• Did not explain the properties of all Did not explain the properties of all

62 elements62 elements

First version of modern periodic table

• 1869• Mendeleev• Arranged according to

increasing atomic mass• Placed elements with similar

properties in same column

• He used the word “periodic” to describe his table• Problems with that setup• Certain elements didn’t “fit”• He predicted that elements

would be discovered – left room

MoseleyMoseley

• X-ray experimentsX-ray experiments• Concept of atomic numberConcept of atomic number• Rearranged the table according to Rearranged the table according to

increasing atomic numberincreasing atomic number• Fixed the problems!Fixed the problems!

Modern Periodic TableModern Periodic Table

•Elements arranged Elements arranged according to increasing according to increasing ATOMIC NUMBERATOMIC NUMBER

Periodic LawPeriodic Law

• States that when the elements are States that when the elements are arranged by increasing atomic arranged by increasing atomic number, there is a periodic number, there is a periodic repetition of their chemical and repetition of their chemical and physical propertiesphysical properties

Arrangement of tableArrangement of table

•Groups (columns) or Groups (columns) or “families” “families”

•VerticalVertical•1-181-18

•Periods Periods •HorizontalHorizontal•1-71-7

• Left of “step” are metals• Right of “step” are

nonmetals• On the “step” are

metalloids

““Representative Representative elements”elements”

•Groups 1,2, and 13-18Groups 1,2, and 13-18•(1A, 2A, 3A-8A)(1A, 2A, 3A-8A)•All “A” groupsAll “A” groups

Group “B” ElementsGroup “B” Elements

•Transition metalsTransition metals–Groups 3 - 12Groups 3 - 12

• Inner Transition elementsInner Transition elements–Lanthanide and Actinide Lanthanide and Actinide seriesseries

MetalsMetals

• MalleableMalleable• DuctileDuctile• Solids Solids • **HgHg* exception – is liquid* exception – is liquid• Good conductors-heat and Good conductors-heat and

electricityelectricity• Lustrous (shiny)Lustrous (shiny)

•Tend to lose Tend to lose electrons when electrons when they bond with they bond with nonmetalsnonmetals

• If start out neutral, and lose If start out neutral, and lose electrons, what charge do they electrons, what charge do they then have?then have?

• Positive!!!!!!!!!!!!!!!!Positive!!!!!!!!!!!!!!!!• Positive ions called Positive ions called cationscations

Group 1 Alkali MetalsGroup 1 Alkali Metals

•VERY REACTIVEVERY REACTIVE•OCCUR IN NATURE OCCUR IN NATURE ONLY IN ONLY IN COMPOUNDSCOMPOUNDS

Group 2 Group 2 ““Alkaline Earth Metals”Alkaline Earth Metals”

•Also very reactive Also very reactive •But Group 1 beats it!!But Group 1 beats it!!

NonmetalsNonmetals

•Solids and gasesSolids and gases•Solids – brittle, lacklusterSolids – brittle, lackluster•Liquid - bromineLiquid - bromine•Poor conductors of heat Poor conductors of heat

electricityelectricity

NONMETALSNONMETALS

• Tend to GAIN electrons when they Tend to GAIN electrons when they bond with metals to form a bond with metals to form a compoundcompound

• If neutral and then GAIN electrons, If neutral and then GAIN electrons, what charge does it have?what charge does it have?

• Negative!!!!Negative!!!!• Negative ions called anionsNegative ions called anions

•ShareShare electrons when they electrons when they bond with other bond with other nonmetalsnonmetals to to form a compoundform a compound

HALOGENS – Group 17 (7A)

• Very reactive Very reactive nonmetalsnonmetals• Occur in nature only in Occur in nature only in

compoundscompounds• Fluorine – most reactive Fluorine – most reactive

nonmetalnonmetal

Halogens

• Only group on the table that has elements Only group on the table that has elements in all three phasesin all three phases

• F, Cl – gasesF, Cl – gases

• Br – liquidBr – liquid

• I – solidI – solid

• Are all diatomic when by themselvesAre all diatomic when by themselves

• FF22, Cl, Cl22, Br, Br22, I, I22

•Group 18 Noble gasesGroup 18 Noble gases•UnreactiveUnreactive•Anyone know the reason Anyone know the reason

why??why??

Valence electronsValence electrons

•Valence electrons and group Valence electrons and group numbernumber

•Valence electrons and Valence electrons and period numberperiod number

““Blocks” of the periodic Blocks” of the periodic tabletable

• ss• pp• dd• ff

f block f block

•Called the “Inner Called the “Inner Transition metals”Transition metals”

•Lanthanides Lanthanides (a.n. 58-71)(a.n. 58-71)

•Actinides (a.n. 90-103)Actinides (a.n. 90-103)

Periodic trendsPeriodic trends

•Atomic radiusAtomic radius–Increases down a groupIncreases down a group–Decrease across a period – Decrease across a period – “shielding effect”“shielding effect”

Ionic radiusIonic radius

• Metals – ions are Metals – ions are smallersmaller than the than the corresponding atomcorresponding atom

• Lost electronsLost electrons• Ionic radius is smaller that its Ionic radius is smaller that its

atomic radiusatomic radius

Ionic radius - nonmetalsIonic radius - nonmetals

• Ions have gained electronsIons have gained electrons

•So, ionic radius is So, ionic radius is largerlarger than its atomic radiusthan its atomic radius

Ionization energyIonization energy

• Amount of energy needed to Amount of energy needed to remove an electron from an atomremove an electron from an atom

• Metals – lowMetals – low• Nonmetals – highNonmetals – high• So, IE So, IE increasesincreases as you go from left as you go from left

to right on the periodic tableto right on the periodic table

• IEIE

•DecreasesDecreases as you go down a as you go down a groupgroup

ElectronegativityElectronegativity

•The ability of an atom to The ability of an atom to attractattract electrons in a electrons in a chemical bondchemical bond

•F has the highest F has the highest electronegativityelectronegativity

ElectronegativityElectronegativity

• IncreasesIncreases as you go from left as you go from left to right on the periodic tableto right on the periodic table

•Decreases as you go down a Decreases as you go down a group (as atomic number group (as atomic number increases)increases)