Chemistry Chapter 5 The Periodic Law

Mendeleev’s Periodic Table Dmitri Mendeleev

Modern Russian Table

Chinese Periodic Table

Stowe Periodic Table

Spiral Periodic Table A Spiral Periodic Table

Triangular Periodic Table

“Mayan” Periodic Table

Orbital filling table

IUPAC naming system with Roman numerals And CAS naming system with letters

Periodic Table with Group Names

The Periodic Law

Properties of Metals  Metals are good conductors of heat and electricity  Metals are malleable (can be hammered into thin sheets)  Metals are ductile (can be pulled into wires)  Metals have luster  Metals tend to lose electrons in order to bond with other elements

Examples 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

Metal Alloys  Substitutional Alloy: some metal atoms replaced by others of similar size. brass = Cu/Zn

Propertiesof Nonmetals Properties of 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  Nonmetals tend to gain electrons to bond

Examples 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

Sulfur – S 8

Phosphorus – P 4

Allotropes -Different forms of the same element. Example: Carbon’s allotropes are diamond, graphite and buckminsterfullerene

Buckminsterfullerene

Graphite

Diamond

Some nonmetals exist as diatomic molecules:Br 2, I 2,N 2, Cl 2, H 2, O 2, F 2 Fluorene, F 2 Chlorine Cl 2 Bromine, Br 2 Nitrogen, N 2 Oxygen, O2 Iodine, I 2 Hydrogen, H 2 (Pop test) BrINClHOF

Properties of Metalloids 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  Metalloids tend to lose or gain electrons to bond

Silicon, 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 due to decreased shielding Radius increases down a group Addition of principal quantum levels Determination of Atomic Radius:

Table of Atomic Radii

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 group Outer electrons are farther from the nucleus Ionization Energy - the energy required to remove an electron from an atom

Ionization of Magnesium Mg kJ  Mg + + e - Mg kJ  Mg 2+ + e - Mg kJ  Mg 3+ + e -

Table of 1 st 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 nucleus experience 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 Affinities

Ionic Radii Cations Positively charged ions Smaller than the corresponding atom Anions Negatively charged ions Larger than the corresponding atom

Summation of Periodic Trends

Table of Ion Sizes

Electronegativity A measure of the ability of an atom in a chemical compound 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