1. Chemistry XXI Unit 3 How do we predict properties? DISCUSSION Central goal: To analyze the nature of the intermolecular forces between the different chemical components of a system.

2. Chemistry XXI In the two-week experiment that you are performing, you have been using a variety of chemical substances with physical and chemical properties that are determined by the nature of the intermolecular forces (IMFs) among their particles. Intermolecular Forces Alizarin Cu(NO 3 ) 2 (aq) Copper (II) Nitrate solution Dimethylglyoxime

3. Chemistry XXI Let’s Think Alizarin a)Describe the e- pair geometry and the molecular geometry around each of the encircled atoms; b)Discuss whether this molecule is polar or not; c)Identify all of the different types of IMFs between two of these molecules; d)Predict whether the substances is a gas, liquid, or solid at STP.

4. Chemistry XXI Alizarin POLAR Dipole-Dipole Induced Dipole- Induced Dipole (Dispersion) H-Bonding (Where? How?) SOLID Trigonal planar/Trigonal planar

5. Chemistry XXI Let’s Think Dimethylglyoxime (dmgH) a)Describe the e- pair geometry and the molecular geometry around each of the encircled atoms; b)Discuss whether this molecule is polar or not; c)Identify all of the different types of IMFs between two of these molecules; d)Predict whether the substances is a gas, liquid, or solid at STP.

6. Chemistry XXI dmgH Tetrahedral/bent POLAR Dipole-Dipole H-Bonding Induced Dipole- Induced Dipole (Dispersion) SOLID Tetrahedral/Tetrahedral Trigonal planar/Trigonal planar Trigonal planar/Bent

7. Chemistry XXI dmgH forms a bright red solid compound when combined with Ni 2+ : Ni(dmgH) 2. This reaction is used for the identification of nickel. Let’s Think The actual complex is formed with this ion. What IMFs help this “complex” to form? - - 2+ Ni

8. Chemistry XXI Metal Complexes - - 2+ H-bonding Ion-Dipole -- 

9. Chemistry XXI Let’s Think a)Identify the three main IMFs present among the components of this Cu(NO 3 ) 2 solution; b)Arrange them in order of increasing strength (from weakest to strongest)

10. Chemistry XXI IMFs ion-ion > ion-dipole > H-bonding (dipole-dipole) If ion-ion are so strong, why is Cu(NO 3 ) 2 dissolved?

11. Chemistry XXI Let’s Think This is the basic structure of a unit of Aluminon. a)Would you expect this to be a molecular or an ionic compound? b)What is the overall molecular geometry of the two main components of this substance? (Pay attention to hidden C and H) c)Would you expect this substance to be soluble in water? Why?

12. Chemistry XXI Aluminon Ionic Compound Formula Unit Tetrahedral Planar Freely soluble in water (ion-dipole, H-bonding, dipole-dipole IMFs)