1. Section 9.5 Electronegativity = ? –Ability to attract electrons When atoms react, the electronegativity between atoms will determine which type of bond is formed

2. Predicting Bond Type Calculate the difference between electronegativities of the elements 1.7 to 4.0 = ionic bond Large differences indicate a transfer of electrons

3. To calculate difference between electronegativity 1.7 to 4.0 = ionic bond NaCl 0.93.0 3.0 – 0.9 = 2.1

4. If difference is between 0.3 and 1.7  polar covalent Electronegativity difference is not strong enough for a transfer of electrons

5. Electrons are shared Unequal sharing of electrons because one atom is more electronegative Electrons spend more time around the more electronegative element and molecules becomes polar Polar Covalent

6. For example… H2OH2O 2.13.5 3.5 – 2.1 = 1.4

7. If electronegativity difference is between 0 and 0.3  nonpolar covalent Atoms are approximately equal in electronegativies Most common in diatomic molecules and hydrocarbons

8. N2N2 3.0 3.0 – 3.0 = 0 N

9. Difference in all of the bonds… IonicPolar CovalentNon-Polar Covalent 1.7  4.00.3  1.70  0.3 High melting point Low melting point SolidsSolids and liquids Liquids and gases No dipolesDipolesNo dipoles Dissolves in polar covalent Dissolve in non- polar covalent

10. ChargeElectro- negativity Elements+_Formula+_DifferenceBond Li + Br H + Br C + O K + O C + Cl Na + Cl

11. ChargeElectro- negativity Elements+_Formula+_DifferenceBond Ca + P Si + F C + N K + O C + I H + P