Electrons and Electrons and Periodic BehaviorPeriodic Behavior

Cartoon courtesy of NearingZero.net

Orbital filling tableOrbital filling table

Electron configuration of Electron configuration of the elements of the first the elements of the first three seriesthree series

Chemical SymbolsChemical Symbols

Symbols used in the 18th Century

Antimony Water Sulfuric acidCopper Sulfur

Symbols used by John Dalton

Carbon

Hydrogen

Oxygen

Silver

Sulfur

Nitrogen

S Lead

Mercury

Copper C

L Gold

Potassa

Soda

G

Water Carbon dioxide Alcohol

Brownlee, Fuller, Hancock, Sohon, Whitsit, First Principles of Chemistry, 1931, page 74

Mendeleev’s Periodic TableMendeleev’s Periodic Table

Dmitri Mendeleev

Modern Russian TableModern Russian Table

Greek ElementsGreek Elements

A Spiral Periodic A Spiral Periodic TableTable

““Mayan” Mayan” Periodic Periodic TableTable

Alchemy !! Alchemy !!

The Periodic TableThe Periodic Table

Period

Group or family

PeriodGroup or Family

Easily lose valence electron (Reducing agents)

React violently with water Large hydration energy React with halogens to

form salts

The Properties of a The Properties of a Group: Group: the Alkali Metalsthe Alkali Metals

Potassium Metal in Potassium Metal in WaterWater

Newmark, CHEMISTRY, 1993, page 25

Groups/Families on the Groups/Families on the Periodic TablePeriodic Table

Noble Gases: Family18Noble Gases: Family18 Alkali Metals: Family 1Alkali Metals: Family 1

in pure state they all have a silvery in pure state they all have a silvery appearance and are soft enough to cut appearance and are soft enough to cut with a knifewith a knife

Extremely reactive so aren’t found as Extremely reactive so aren’t found as free elementsfree elements

Noble GasesNoble Gases

Groups/Families on the Groups/Families on the Periodic TablePeriodic Table

Alkaline-earth metals: Group 2 Alkaline-earth metals: Group 2 harder, denser, and stronger than group harder, denser, and stronger than group

1 or alkali metals1 or alkali metals Have higher melting points than group 1, Have higher melting points than group 1,

and are less reactive (although still and are less reactive (although still reactive enough not to be found as free reactive enough not to be found as free elements)elements)

Halogens: Group 17Halogens: Group 17 Most reactive nonmetalsMost reactive nonmetals

Carbon….The Carbon….The Essence of Life Essence of Life

Special elementsSpecial elements

Hydrogen and Helium are special b/c although Hydrogen and Helium are special b/c although they share some characteristics with their they share some characteristics with their groups/families, they are different b/c they groups/families, they are different b/c they have properties that are not similar to those of have properties that are not similar to those of ANY groupANY group

Hydrogen and helium are the simplest and Hydrogen and helium are the simplest and most abundant elements. Hydrogen makes up most abundant elements. Hydrogen makes up 76% of the mass of the universe and helium 76% of the mass of the universe and helium makes up 23%makes up 23%

Life or Death ElementsLife or Death Elements

Properties of MetalsProperties of Metals Metals are good conductors of heat and electricity

Metals are malleable

Metals are ductile

Metals have high tensile strength

Metals have luster

Examples of MetalsExamples of Metals

Potassium, K reacts with water and must be stored in kerosene

Zinc, Zn, is more stable than potassium

Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Mercury, Hg, is the only metal that exists as a liquid at room temperature

PropertiesProperties of Nonmetalsof Nonmetals

Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element. Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature

Examples of NonmetalsExamples of Nonmetals

Sulfur, S, was once known as “brimstone”

Microspheres of phosphorus, P, a reactive nonmetal

Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

Properties of Properties of MetalloidsMetalloids

Metalloids straddle the border between metals and nonmetals on the periodic table.

They have properties of both metals and nonmetals.Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster

Silicon, Si – A MetalloidSilicon, Si – A Metalloid

Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity

Other metalloids include:

Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te

AspirinAspirin

Half of the distance between nuclei in covalently bonded diatomic molecule

"covalent atomic radii"

Periodic Trends in Atomic Radius

Radius decreases across a period Increased magnetic attraction

Radius increases down a group Addition of principal quantum levels

Determination of Atomic Radius:Determination of Atomic Radius:

Table of Table of Atomic Atomic RadiiRadii

Tends to increase across a period

Atoms become closer to a full electron octet in the outer energy level

Tends to decrease down a groupOuter electrons are farther from thenucleus

Ionization EnergyIonization Energy - the energy - the energy required to remove an electron required to remove an electron from an atomfrom an atom

Table of 1Table of 1stst Ionization Energies Ionization Energies

Ionization of MagnesiumIonization of Magnesium Mg + 738 kJ Mg+ + e-

Mg+ + 1451 kJ Mg2+ + e-

Mg2+ + 7733 kJ Mg3+ + e-

Another Way to Look at Another Way to Look at Ionization EnergyIonization Energy

ElectronegativityElectronegativityA measure of the ability of an atom in a chemicalcompound to attract electrons

Electronegativities tend to increase across a period (full octet)

Electronegativities tend to decrease down a group or remain the same

Periodic Table of Periodic Table of ElectronegativitiesElectronegativities

Summation of Periodic TrendsSummation of Periodic Trends