Post on 03-Jan-2016
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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