Q3 Week-1 Intermolecular Forces of Attraction PDF

Kinetic Molecular Model of Liquids and Solids Intermolecular Forces OF ATTRACTION LESSON 1 A OBJECTIVES: 1.Apply the kinetic molecular theory to describe liquids and solids. 2.Compare the properties of liquids and solids with those of gases. 3.Describe and differenti...

Kinetic Molecular Model of Liquids and Solids Intermolecular Forces OF ATTRACTION LESSON 1 A OBJECTIVES: 1.Apply the kinetic molecular theory to describe liquids and solids. 2.Compare the properties of liquids and solids with those of gases. 3.Describe and differentiate the types of intermolecular forces. Recall! Directions: Recall the concepts on Molecular Geometry, Polarity, Bond Dipole and Dipole Moment. Complete the table below by following these instructions: 1.Draw the Lewis structures of the following molecules with the correct shape around the central atom. 2.Indicate each bond’s polarity by drawing an arrow to represent the bond dipole along each bond. 3.Determine the molecule’s polarity and indicate this with an arrow to represent the dipole. 4.Circle your choice in each box to mark the molecule as polar or nonpolar. Cl2 NH3 CH3Br CH4 polar or polar or polar or polar or nonpolar nonpolar nonpolar nonpolar THE EFFECT OF BOILING POINT AND FREEZING POINT ON THE DISSOLUTION OF SOLIDS IN WATER Kinetic Molecular Models of Liquids and Solids  Phase A homogeneous part of a system in interacting with other parts of the system but separated from these other parts by well-defined boundaries. Condensed phases Liquids and solids Intramolecular forces and intermolecular forces Intermolecular forces are attractive forces between molecules. Intramolecular forces hold atoms together in a molecule.  A. Kinetic Molecular Models of Liquids and Solids The experimental findings about the behavior of gases can be explained with a simple theoretical model known as the kinetic molecular theory. This theory is based on the following assumptions: 1.All matter is made of tiny particles. 2.These particles are in constant motion. 3.The speed of particles is proportional to temperature. Increased temperature means greater speed. 4.Solids, liquids, and gases differ in distances between particles, in the freedom of motion of particles, and in the extent to which the particles interact. https://preparatorychemistry.com/KMT_Canvas.html Intermolecular forces are attractive forces between molecules. (Example: water molecule to water molecule) Intramolecular forces hold atoms together within in a molecule. (Example: H to O bond within a water molecule). Intermolecular vs Intramolecular 41 kJ to vaporize 1 mole of water (inter) 930 kJ to break all O-H bonds in 1 mole of water (intra) “Measure” of intermolecular force Generally, boiling point intermolecular forces are much melting point weaker than Hvap intramolecular forces. Hfus Hsub 11.2  Intermolecular Forces 1. London Forces (a.k.a. Dispersion Forces) Weakest 2.Dipole-Dipole Interactions 3.Ion-Dipole Interactions -(Salt dissolving in solution; Na+ and Cl- ) 4. Hydrogen Bonding (STRONGEST)  London Dispersion Forces: Weakest Occur between every compound and arise from the net attractive forces amount molecules which is produced from induced charge imbalances The larger the molecule the greater Figure 2. it’s Dispersion (a) Spherical charge Forces are distribution in a helium atom. (b) Distortion caused by the approach of a cation. (c) Distortion caused by the approach of a dipole. Image obtained from http://www.mikeblabe r.org/oldwine/chm104 5/notes/Forces/Interm ol/Forces02.html The boiling point of long molecules increase with the length of the carbon chain. How molecular shape affects the strength of the dispersion forces The shapes of the molecules also matter. Long thin molecules can develop bigger temporary dipoles due to electron movement than short fat ones containing the same numbers of electrons. Butane has a higher boiling point because the dispersion forces are greater.http://www.chemguide.co.uk/atoms/bonding/vdw.html  Polarizability - the ease with which the electron distribution in the atom or molecule can be distorted. Polarizability increases with: greater number of electrons more diffuse electron cloud Dispersion forces usually increase with molar mass. 11.2  Is the Molecule Polar? The more Electronegative atom will pull the electron density of the bond closer to itself giving it a partial negative charge leaving the other atom with a partially positive charge. This is a dipole moment.  Molecules with 3 Atoms Even though the C-O bond is polar, the bonds cancel each other out because the molecule is linear the dipole moments are equal and in opposite directions. Therefore CO2 is non- CO2 polar. The dipole moment between H-C points in the direction of C. The dipole moment points between C-N points in the direction of the N. Therefore the dipole HCN vectors are additive and HCN is polar SO2 is a polar molecule because the S-O dipole Moments don’t cancel each other out due to the angle SO2 Molecules with 4 Atoms CCl4 is non-polar CHCl3 is polar  How to Determine if a Molecule Is Polar 1.Draw Lewis Structure 2.If all of the regions of electron density are bound to the same thing (CCl4; CO2 ) then the molecule is non-polar 3.If the regions of electron density are not bound to the same thing (atom) than the molecule is polar (HCN; SO2)  Which of the following molecules are polar (have a dipole moment)?H2O, CO2, SO2, and CH4 O S H O H O dipole moment dipole moment polar molecule polar molecule H H C H O C O no dipole moment H nonpolar no dipole moment molecule nonpolar molecule 10.2  Dipole-Dipole Forces Attractive forces between polar molecules Orientation of Polar Molecules in a Solid Animation: http://chemmovies.unl.edu/ChemAnime/DIPOLED/DIPOLED.html 11.2 Dipole Forces occur between molecules containing a dipole moment. The positive end of the dipole moment on one mole is attracted to the negative end of the dipole moment on a nearby molecule. Figure 10-11 2-methyl propane (left) and acetone (right) Both compounds are about Equal in size and shape Olmsted Williams  Ion-Dipole Forces Attractive forces between an ion and a polar molecule Ion-Dipole Interaction The larger the charge the stronger the force 11.2  Figure 4. (a)Interaction of a water molecule with a Na+ ion and a Mg 2+ ion. (b) In aqueous solutions, metal ions are usually surrounded by six water molecules in an octahedral arrangement. Image obtained from https://www.slideshare.net/Mr-Midgley/intermolecular-forces-15275077 A molecular picture showing the ion-dipole Interaction that helps a solid ionic crystal dissolve in water. The arrows indicate ion-dipole interactions.  What type(s) of intermolecular forces exist between each of the following molecules? HBr HBr is a polar molecule: dipole-dipole forces. There are also dispersion forces between HBr molecules. CH4 CH4 is nonpolar: dispersion forces. S O SO2 O SO2 is a polar molecule: dipole-dipole forces. There are also dispersion forces between SO2 molecules. 11.2  The Hydrogen Bond STRONGEST INTERMOLECULAR FORCE  water has water water thehashas water thehas highest water theheat has highest highest the the heat lowest highest of of fusion melting molar vaporization mass point boiling point The melting point, boiling point, heat of fusion and heat of vaporization of water are extremely high and do not fit the trend of properties relative to molar mass within Group VIA. Water exhibits these unusual properties because of hydrogen bonding between water molecules.  A hydrogen bond is an intermolecular bond. A hydrogen bond is formed between polar molecules that contain hydrogen covalently bonded to a small, highly electronegative atom: F, O, N. F—H O—H N—H  it will be attracted to another F, O, or N, on another molecule. A dipole-dipole bond will be formed between the two molecules which is called a hydrogen bond. hydrogen bond covalent bond covalent bond  Water in the liquid and solid states exists as groups in which the water molecules are linked together by hydrogen bonds. 13.8 Activity 4. Analyze! Directions: Read and answer each question carefully. 1. (a) Does the diagram best describe a crystalline solid, a liquid, or a gas? (b) Explain. 2. List the three states of matter in their order of (a) increasing molecular disorder and (b) increasing intermolecular attraction. (c) Which state of matter is most easily compressed?  Application of KMT Modern refrigeration is a practical application of the kinetic molecular theory. When freon gas is compressed, the walls moving inward (or piston) adds kinetic energy to the molecules which in turn causes the gas to increase in temperature. The warmed gas is allowed to pass through external cooling coils to dissipate the extra heat into the environment, then the gas expands again (walls moving away slow down molecules) to become cooler and absorb heat inside fridge then start the cycle again. In a cruder form, you could for instance cool a can a soda if the compressed gas above the liquid was a larger volume by just opening it, through it might require a thicker material for the can. You may watch this tutorial video for additional information. PERFORMANCE TASK NO. 1 Comical sketch Directions: Make a comical sketch using three heroes as particles (or molecules) and present their behavior and positions relative to each other in the solid, liquid and gaseous state. Assign one hero as the solid, the second as liquid and Thank you for listening!