
Periodic Table • Dmitri Mendeleev developed the modern periodic table. Argued that element properties are periodic functions of their atomic weights. • We now know that element properties are periodic functions of their ATOMIC NUMBERS.
6.1 Metals, Nonmetals, and Metalloids • Three classes of elements are metals, nonmetals, and metalloids. • Across a period, the properties of elements become less metallic and more nonmetallic.
6.1 Metals, Nonmetals, and Metalloids • Metals, Metalloids, and Nonmetals in the Periodic Table
6.1 Metals, Nonmetals, and Metalloids • Metals, Metalloids, and Nonmetals in the Periodic Table
6.1 Metals, Nonmetals, and Metalloids • Metals, Metalloids, and Nonmetals in the Periodic Table
6.1 Metals, Nonmetals, and Metalloids • Metals, Metalloids, and Nonmetals in the Periodic Table
6.1 Metals, Nonmetals, and Metalloids • Metals • Metals are good conductors of heat and electric current. • 80% of elements are metals. • Metals have a high luster, are ductile, and are malleable.
6.1 Metals, Nonmetals, and Metalloids • Uses of Iron, Copper, and Aluminum
6.1 Metals, Nonmetals, and Metalloids • Uses of Iron, Copper, and Aluminum
6.1 Metals, Nonmetals, and Metalloids • Uses of Iron, Copper, and Aluminum
6.1 Metals, Nonmetals, and Metalloids • Nonmetals • In general, nonmetals are poor conductors of heat and electric current. • Most nonmetals are gases at room temperature. • A few nonmetals are solids, such as sulfur and phosphorus. • One nonmetal, bromine, is a dark-red liquid.
6.1 Metals, Nonmetals, and Metalloids • Metalloids • A metalloid generally has properties that are similar to those of metals and nonmetals. • The behavior of a metalloid can be controlled by changing conditions.
Element Abundance C O Al Si Fe http://www.webelements.com/webelements/elements/text/Si/geol.html
Hydrogen Shuttle main engines use H2 and O2 The Hindenburg crash, May 1939.
Group 1A: Alkali Metals Reaction of potassium + H2O Cutting sodium metal
Group 2A: Alkaline Earth Metals Magnesium Magnesium oxide
Calcium Carbonate—Limestone Champagne cave carved into chalk in France The Appian Way, Italy
Group 3A: B, Al, Ga, In, Tl Aluminum Boron halides BF3 & BI3
Gems & Minerals • Sapphire: Al2O3 with Fe3+ or Ti3+ impurity gives blue whereas V3+ gives violet. • Ruby: Al2O3 with Cr3+ impurity
Group 4A: C, Si, Ge, Sn, Pb Quartz, SiO2 Diamond
Group 5A: N, P, As, Sb, Bi White and red phosphorus Ammonia, NH3
Phosphorus • Phosphorus first isolated by Brandt from urine, 1669
Group 6A: O, S, Se, Te, Po Sulfuric acid dripping from snot-tite in cave in Mexico Sulfur from a volcano
XeOF4 Group 8A: He, Ne, Ar, Kr, Xe, Rn • Lighter than air balloons • “Neon” signs
Transition Elements Lanthanides and actinides Iron in air gives iron(III) oxide
Lithium Group 1A Atomic number = 3 1s22s1 ---> 3 total electrons
Beryllium Group 2A Atomic number = 4 1s22s2 ---> 4 total electrons
Boron Group 3A Atomic number = 5 1s2 2s2 2p1 ---> 5 total electrons
Carbon Group 4A Atomic number = 6 1s2 2s2 2p2 ---> 6 total electrons
Nitrogen Group 5A Atomic number = 7 1s2 2s2 2p3 ---> 7 total electrons
Oxygen Group 6A Atomic number = 8 1s2 2s2 2p4 ---> 8 total electrons
Fluorine Group 7A Atomic number = 9 1s2 2s2 2p5 ---> 9 total electrons
Neon Group 8A Atomic number = 10 1s2 2s2 2p6 ---> 10 total electrons
Colors of Transition Metal Compounds Nickel Cobalt Copper Zinc Iron
Higher effective nuclear charge Electrons held more tightly Larger orbitals. Electrons held less tightly. General Periodic Trends • Atomic and ionic size • Ionization energy • Electron affinity • Electronegativity
Effective Nuclear Charge, Z* • Explains why E(2s) < E(2p) • Z* is the nuclear charge experienced by the outermost electrons. Is the result of the nuclear attraction being blocked by the core electrons. Nuclear attraction increases with an increase in protons • Estimate Z* by --> [ Z - (no. core electrons) ] • Charge felt by 2s e- in Li Z* = 3 - 2 = 1 • Be Z* = 4 - 2 = 2 • B Z* = 5 - 2 = 3 and so on!
Effective Nuclear Charge, Z* • Shielding effect remains constant across a period. As the nuclear attraction increases across the shielding effect is less effective. • Shielding effect increases down a group thus effectively blocking any increase in nuclear attraction. • Electrons with a higher quantum number have more kinetic energy and thus are less affected by the nuclear charge. • Each of these forces need to be accounted for in each trend.
Effective Nuclear Charge, Z* • Atom Z* Experienced by Electrons in Valence Orbitals • Li +1.28 • Be ------- • B +2.58 • C +3.22 • N +3.85 • O +4.49 • F +5.13 Increase in Z* across a period
Periodic Trend in the Reactivity of Alkali Metals with Water Lithium Sodium Potassium
Atomic Size • Size goes UP on going down a group. • Because electrons are added further from the nucleus, there is less attraction, due to an increase in sheilding effectiveness and in increase in kinetic energy.
Atomic Size • Size goes UP on going down a group. • Because electrons are added further from the nucleus, there is less attraction, due to an increase in sheilding effectiveness and in increase in kinetic energy.
General Outline for Trends • Trend-define • Down a group • Nuclear attraction-define once • Trend, effect • Shielding effect-define once • Trend, effect • Kinetic energy-define once • Trend, effect • Across a period • Nuclear attraction • Trend, effect • Shielding effect • Trend, effect • Kinetic energy • Trend, effect
Atomic Radius • Atomic radius is the distance from the nucleus to the valance electrons. • Nuclear attraction (the attraction of the protons in the nucleus on valance electrons) increases going down a group. This should pull the electrons in closer to the nucleus. • Shielding effect (the blocking of nuclear attractions by core electrons) Shielding effect increases down a group offsetting the increase in nuclear attraction. • Kinetic energy (the energy of valance electrons associated with principle energy levels) increases down a group allowing the valance electrons to orbit farther from the nucleus increasing atomic radius.