H3.06Ga1.34 Li1.28Ge1.95 Be1.99As2.26 B1.83Se2.51 C2.67Br3.24 N3.08Kr2.98 O3.21**Rb0.99 *F4.42Sr1.21 *Ne4.60In1.30 Na1.21Sn1.83 Mg1.63Sb2.06 Al1.37Te2.34 Si2.03I2.88 P2.39Xe2.59 S2.65 Cl3.54 Ar3.36 **K1.03 Ca1.30 Electronegativity: An atom's attraction for electrons in a bond. In other words, it is a measure of the drawing power of an atom when it is part of a compound. The greater the atom's power to attract electrons, the greater the electronegativity. Noble gases are highest in their attraction because they don’t want to let any of their valence electrons go. Pink = highest Yellow = lowest

Ionization Energy: Amount of energy required to remove one electron from an atom. In other words, the more valence electrons needed to be removed the greater the ionization energy Group 1: 1 valence electron Group 17: 7 valence electrons Which group requires more energy to remove its electrons? Which element has the highest Ionization energy? Which element has the lowest ionization energy? F Fr

First Ionization Energy Plot Atomic number First ionization energy (kJ/mol) H He Li Be B C N O F Ne Mg Na Al Si P S Cl Ar Ca K Sc Ti V Cr Mn Fe Co Cu Ni Zn Ga Ge As Se Br Rb Sr Kr

Atomic Radius: The size of an atom. As the atom gets smaller, the valence electrons become closer to the nucleus. This means the attractive force holding the electron is stronger and it takes more energy to pull the electron off. Trends in atomic radius in Periods 2 and 3

Periodic Trends in Atomic Radii LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World, 1996, page 175

Relative Size of Atoms Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 350

IONIC RADIUS: Ions aren't the same size as the atoms they come from. Compare the sizes of sodium and chloride ions with the sizes of sodium and chlorine atoms. Cations decrease in size by losing electrons, Anions increase in size by gaining electrons.

Sizes of ions: electron repulsion Valence electrons repel each other When an atom becomes a anion (adds an electron to its valence shell) the repulsion between valence electrons increases without changing ENC Thus, F – is larger than F Fluorine atom F 1s 2 2s 2 2p F 1- 1s 2 2s 2 2p 6 +1e Fluorine ionFluoride ion

IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom Li 1+ Be 2+ Na 1+ Mg 2+ Ba 2+ Sr 2+ Ca 2+ K 1+ Rb 1+ Cs 1+ Cl 1- N 3- O 2- F 1- S 2- Se 2- Br 1- Te 2- I 1- Al 3+ Ga 3+ In 3+ Tl 3+ Ionic Radii

Trends in Atomic and Ionic Size Li Na K 60 Li + 95 Na+ 133 K+ e e e F-F- 136 Cl Br F Cl Br e e e MetalsNonmetals Group 1 Al e e e Group 13 Group 17 Cations are smaller than parent atomsAnions are larger than parent atoms Al 3+

152 Li 60 Li + e Li + e e e e Li Lithium atom Lithium ion Li Lithium atom Li Energy

IA IIA IIIA IVA VA VIA VIIA Li 1+ Be 2+ Na 1+ Mg 2+ Cl 1- N 3- O 2- F 1- S 2- Se 2- Br 1- Te 2- I 1- Al 3+ Ga 3+ In 3+ Tl 3+ Ca 2+ K 1+ Sr 2+ Rb 1+ Cs 1+ Ba 2+ Li Na K Rb Cs Cl S P Si Al Br Se As Ge Ga I Te SbSn In Tl Pb Bi Mg Ca Sr Ba BeBCNOF = 1 Angstrom Atomic Radii Ionic Radii Cations: smaller than parent atoms Anions: LARGER than parent atoms

Summation of Periodic Trends