IIIIII III. Periodic Trends (p ) Ch. 6 - The Periodic Table

A. Periodic Law zWhen elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals. Each interval corresponds to a family.

A. Know 6 Trends for TEST M R E I R O increasing trends Metallic Character: loosely held electrons Radius (size of atom) Electron Affinity (electronegativity) Ionization Energy (first ionization E only) Reactivity (bonding) of Metals losing e- or Nonmetals gaining e- Oxidation State (ionic charge)

A. Periodic Trends described zMost trends of chemical properties on the periodic table can be explained by Radius (size) of atom: effects the nuclear attraction, the electromagnetic attraction of positive nucleus and negative electrons Octet Rule: all atoms want to achieve 8 valence electrons, a stable noble gas configuration and so will react (bond) in ways to do that Metals will lose electrons to do this and Nonmetals will gain electrons

zMetals = loosely held electrons causing properties like being malleable, ductile, luster, and good conductors of electricity and heat zNonmetals = tightly held electrons making them be brittle, dull, and insulators (bad conductors) zMetalloids = have properties of both in different circumstances B. Metallic Character M M

zAtomic Radius (size of atom) yas # of shells increase the size gets bigger and the nuclear attraction (+ nucleus for – electrons) for the valence electrons is decreased © 1998 LOGAL C. Radius R

zAtomic Radius C. Atomic Radius Li Ar Ne K Na

zAtomic Radius yIncreases to the LEFT and DOWN C. Atomic Radius

zWhy larger atoms going down? yHigher energy levels have larger shells further from nucleus yShielding - core e - block the attraction between the nucleus and the valence e - alonging valence electrons to be lost more easily zWhy smaller to the right? yIncreased nuclear charge within the same shell, without additional shielding, pulls e - in tighter C. Atomic Radius

zIonic Radius of yCations (+) lose e - and become smaller due to less shells yAnions (–) gain e - and stay about the same size C. Radius changes as neutral atoms become ions

zMeasure of the tendency to gain electrons (also called electronegativity) yElectron affinity is low for metals so easy to remove e- yElectron affinity is high for nonmetals due to smaller size and need a just a few more e- to reach the stable octet D. Electron Affinity E

zThe Pauli Scale measures electronegativity on a scale of 0 to maximum of 4 D. Also called Electronegativity E

yIncreases UP and to the RIGHT E. Electron Affinity XXXXXXXXXXXX F

zThis is the amount of energy required to remove the first outer electron yIonization energy is low for metals so easy to remove electrons yIonization is high for nonmetals and especially the noble gases because electrons are held tightly E. Ionization Energy I

zFirst Ionization Energy E. Ionization Energy K Na Li Ar Ne He

zFirst Ionization Energy yIncreases UP and to the RIGHT E. Ionization Energy

zWhy opposite of atomic radius? yIn small atoms, e - are close to the nucleus where the attraction is stronger zWhy higher near the noble gases? yStable e - configurations (or very close to 8 valence e - ) don’t want to lose e - E. Ionization Energy

zSuccessive Ionization Energies yMg1st I.E.736 kJ 2nd I.E.1,445 kJ Core e - 3rd I.E.7,730 kJ yLarge jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy

yAl1st I.E.577 kJ 2nd I.E.1,815 kJ 3rd I.E.2,740 kJ Core e - 4th I.E.11,600 kJ zSuccessive Ionization Energies yLarge jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy

F. Chemical Reactivity R zAlkali Metals = most reactive metals, explosive with water zAlkaline Earth Metals = also reactive zTransition Metals = less reactive zHalogens = most reactive nonmetals zNoble Gases = inert, nonreactive XXXXXXXXXXXX

G. Oxidation State O +3 +/ yFamilies IA to VIIIA correspond to having that number of valence electrons (remember all want 8 valence e) yCharges are positive when valence electrons are lost; Charges are negative when valence e - ’s are gained +1 +2

zThis is the general trend but… transition metals can have a range of charges from +1 to +7 G. Oxidation State + - C

zMelting/Boiling Point yHighest in the middle of a period. H. Melting/Boiling Point

zWhich atom has the larger radius? yBe orBa yCa orBr Ba Ca Examples

zWhich atom has the higher 1st I.E.? yNorBi yBaorNe N Ne Examples

zWhich atom can have an oxidation state of +1? yLiorC ySorKr Li S Examples zWhich atom can have an oxidation state of -2?

zWhich particle has the larger radius? ySorS 2- yAlorAl 3+ S 2- Al Examples