Chemistry Chapter 5Chemistry Chapter 5

The Periodic LawThe Periodic Law

Mendeleev’s Periodic Table

Dmitri Mendeleev

Modern Russian Table

Chinese Periodic Table

Stowe Periodic Table

A Spiral Periodic Spiral Periodic TableTable

Triangular Periodic Table

““Mayan” Mayan”

Periodic Periodic TableTable

Giguere Periodic TableGiguere Periodic Table

Orbital filling table

Periodic Table with Group Names

Easily lose valence electron (Reducing agents)

React violently with water Large hydration energy React with halogens to form

salts

The Properties of a Group: the Alkali Metals

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 of NonmetalsNonmetals

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

Half of the distance between nucli in covalently bonded diatomic molecule

"covalent atomic radii"

Periodic Trends in Atomic Radius

Radius decreases across a period Increased effective nuclear charge dueto decreased shielding

Radius increases down a group Addition of principal quantum levels

Determination of Atomic Radius:

Table of Table of Atomic Atomic

RadiiRadii

Increases for successive electrons taken from the same atom

Tends to increase across a period

Electrons in the same quantum level do not shield as effectively as electrons in inner levels

    Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove

Tends to decrease down a groupOuter electrons are farther from thenucleus

Ionization Energy - the energy required to remove an

electron from an atom

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

Mg+ + 1451 kJ Mg2+ + e-

Mg2+ + 7733 kJ Mg3+ + e-

Table of 1st Ionization Energies

Another Way to Look at Ionization Energy

Affinity tends to increase across a period

Affinity tends to decrease as you go down in a period

Electrons farther from the nucleusexperience less nuclear attraction

Some irregularities due to repulsive forces in the relatively small p orbitals

Electron Affinity - the energy change associated with the addition of an electron

Table of Electron AffinitiesTable of Electron Affinities

Ionic RadiiIonic RadiiCations

Positively charged ions Smaller than the

corresponding atomAnions

Negatively charged ions Larger than the corresponding atom

Summation of Periodic Trends

Table of Ion Sizes

ElectronegativityElectronegativity

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

Electronegativities tend to increase across a period

Electronegativities tend to decrease down a group or remain the same

Periodic Table of Electronegativities