2. Ionic Radii Trend

3. Sizes of ions: electron repulsion Valence electrons repel each other. 9 +9 + 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 5 9+ - - - - - - - - - F 1- 1s 2 2s 2 2p 6 +1e - 9+ - - - - - - - - - - Fluorine ionFluoride ion

4. Atomic Radii 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 Be F O N C B 1.52 1.11 1.86 1.60 2.31 1.97 2.44 2.15 2.62 2.17 0.88 0.77 0.70 0.66 0.64 1.43 1.17 1.10 1.04 0.99 1.22 1.22 1.21 1.17 1.14 1.62 1.40 1.41 1.37 1.33 1.71 1.75 1.46 IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom 0.60 0.31 0.95 0.65 1.33 0.99 1.48 1.13 1.69 1.35 1.71 1.40 1.36 0.50 1.84 1.81 0.62 1.98 1.85 0.81 2.21 2.16 0.95 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

5. Trends in Atomic and Ionic Size 152 186 227 Li Na K 60 Li + 95 Na+ 133 K+ e e e F-F- 136 Cl - 181 Br - 195 F Cl Br 64 99 114 e e e MetalsNonmetals Group 1 Al 143 50 e e e Group 13 Group 17 Cations are smaller than parent atomsAnions are larger than parent atoms Al 3+

6. 152 Li 60 Li + e 152 60 Li + e e e e Li Lithium atom Lithium ion + 152 Li Lithium atom Li Energy

7. IA IIA IIIA IVA VA VIA VIIA 0.60 0.31 0.95 0.65 1.33 0.99 1.48 1.13 1.69 1.35 1.71 1.40 1.36 0.50 1.84 1.81 0.62 1.98 1.85 0.81 2.21 2.16 0.95 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 1.52 1.11 1.86 1.60 2.31 1.97 2.44 2.15 2.62 2.17 0.88 0.77 0.70 0.66 0.64 1.43 1.17 1.10 1.04 0.99 1.22 1.22 1.21 1.17 1.14 1.62 1.40 1.41 1.37 1.33 1.71 1.75 1.46 BeBCNOF = 1 Angstrom Atomic Radii Ionic Radii Cations: smaller than parent atoms Anions: LARGER than parent atoms

8. Isoelectronic Species 11+ - - - - - - - - - - 12+ - - - - - - - - - - Oxygen ion O 2- 1s 2 2s 2 2p 6 Fluorine ion F 1- 1s 2 2s 2 2p 6 Sodium ion Na 1+ 1s 2 2s 2 2p 6 Magnesium ion Mg 2+ 1s 2 2s 2 2p 6 8+ - - - - - - - - - - 9+ - - - - - - - - - - 10+ - - - - - - - - - - Neon atom Ne 1s 2 2s 2 2p 6 Isoelectronic Isoelectronic - all species have the same number of electrons. Can you come up with another isoelectronic series of five elements? Predict the relative ionic sizes within your isoelectronic series. p = 8 n = 8 e = 10 p = 9 n = 9 e = 10 p = 10 n = 10 e = 10 p = 11 n = 11 e = 10 p = 12 n = 12 e = 10