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Periodic Trends REvisited

Mendeleev’s Periodic Table Dmitri Mendeleev

Periodic Law (Periodicity) Properties repeat at regular intervals when elements are arranged according to increasing atomic number Group/family = column; Period = row

Period The Periodic Table Group or Family Group or family Period

The Properties of a Group: the Alkali Metals Easily lose valence electron (Reducing agents) React violently with water Large hydration energy React with halogens to form salts

Properties of Metals Metals are good conductors of heat and electricity Metals are malleable Metals are ductile Metals have high tensile strength Metals have luster

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

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

Inner Transition/Rare Earth Metals Transition Metals Alkaline Earth Metals Noble Gases Inner Transition/Rare Earth Metals Halogens Alkali Metals

Metal/Metalloid/Nonmetal Metals Metalloids Nonmetals

Representative Elements (1,2,13 – 18) 1 B  10 B

INC INC Atomic Number = # of protons Atomic Mass = # of protons & neutrons INC INC

Shielding= e- between nucleus and outer e- Nuclear Pull= electrostatic attraction of the + nucleus for the outer e- Shielding= e- between nucleus and outer e- INC Constant

e- are added to successively higher energy levels. Atomic Radius = the distance between the nucleus and the outermost electrons. e- are added to successively higher energy levels. We remain in the same principle energy level. Each element has one p+ and one e- more than the preceding element. The nuclear pull increases pulling each new e- closer to the nucleus. INC INC INC

Increasing atomic radii H 0.030 Na 0.157 K 0.203 In 0.150 Sr 0.191 Rb 0.216 Sn 0.140 Sb Te 0.137 I 0.133 Ca 0.174 Ga 0.125 Ge 0.122 As 0.121 Se 0.117 Br 0.114 Mg 0.136 Al Si P 0.110 S 0.104 Cl 0.099 Li 0.123 Be 0.089 B 0.080 C 0.077 N 0.070 O 0.066 F 0.064 The atomic radii of these representative elements are given in nanometers (nm). Increasing atomic radii

Period Trend: Atomic Radius

Ionic Radius (Size) Size or radius of an ion INC Cations Anions The overall trend is the same as Atomic size – for the same reasons, however: Cations have lost e- so they are smaller Anions have gained e- so they are larger

The ionic radii shown here are given in nanometers. 0.140 F- 0.136 Be2+ 0.031 Li+ 0.060 Cs+ 0.169 Tl3+ 0.095 K+ 0.133 Ca2+ 0.099 Na+ N3- 0.171 Cl- 0.181 S2- 0.184 P3- 0.212 As3- 0.222 Ba2+ 0.135 Rb+ 0.148 Sr2+ 0.113 In3+ 0.081 Sn4+ 0.071 I- 0.216 Te2- 0.221 Sb3- 0.245 Ga3+ 0.062 Ge4+ 0.053 Se2- 0.198 Br- 0.195 Pb4+ 0.084 Al3+ 0.050 Mg2+ 0.065 Si4+ 0.041 B3+ 0.020 C4+ 0.015 The ionic radii shown here are given in nanometers.

New TRENDS e- Configuration = arrangement of e- around nucleus s d p f

Electronegativity = tendency of an atom to attract (pull) bonded e- to itself (noble gasses omitted)

Periodic Table of Electronegativities

Electronegativity

Valence Electrons = outermost e- (e- in the highest principle energy level) 1 2 3 4 5 6 7 2 8

Ionic Charge (oxidation number) = charge of atom once it has lost or gained electrons +1 +2 +3 ±4 -3 -2 -1

↑ harder to remove e- as atom gets smaller. Ionization Energy = how much energy it takes to remove an e- from a gaseous atom. (1st ionization energy trend) ↑ harder to remove e- as atom gets smaller. INC

Table of 1st Ionization Energies

1st Ionization Energy = energy to remove 1st e- 2nd “ “ = “ “ “ 2nd e- Atoms want to have the e- configuration of a Noble gas. Atoms are more stable when they have full or ½ full sublevels. Atoms will easily lose or gain e- until they have a noble gas configuration. After that it will take a lot of energy to remove any e-.

Ionization Energy

Summation of Periodic Trends