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STATES OF MATTER #1 ATTRACTIONS

Learn about the Van der Waals attraction, dipole interactions, hydrogen bonds, and electrostatic attractions in various substances. Explore how these forces affect boiling points, melting points, hardness, and states of matter.

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STATES OF MATTER #1 ATTRACTIONS

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  1. The Van der Waals attraction (London Dispersion): • Temporary (induced) dipole – transient. • Occurs in all particles. • The major attraction in NONPOLAR substances. • BECOMES STRONGER AS MOLECULAR MASS INCREASES. As molecular mass increases GREATER temporary polarity CAUSES More electrons in the particle CAUSES STATES OF MATTER #1 ATTRACTIONS CAUSES • EFFECTS OF STRONGER ATTRACTIONS. • HIGHER BOILING TEMP. • HIGHER MELTING TEMP • INCREASING HARDNESS OF SOLID STATE. STRONGER INDUCED DIPOLE ATTRACTIONS CAUSES

  2. The Van der Waals attraction (London Dispersion): • VERY IMPORTANT IN NON-POLAR COVALENT SUBSTANCES INCLUDING H2,O2,N2,Cl2,Br2,I2,F2 and CO2 and CH4. • THE PREDOMINANT ATTRACTION IN THE METALLIC SUBSTANCES (Au, Ag, Cu, Zn, Na etc), WHERE IT IS VERY STRONG AS MANY METALS HAVE LARGE ATOMIC MASSES. As molecular mass increases GREATER temporary polarity CAUSES More electrons in the particle CAUSES CAUSES STRONGER INDUCED DIPOLE ATTRACTIONS CAUSES • EFFECTS OF STRONGER ATTRACTIONS. • HIGHER BOILING TEMP. • HIGHER MELTING TEMP • INCREASING HARDNESS OF SOLID STATE.

  3. THE DIPOLE ATTRACTION • AN INTERMOLECULAR ATTRACTION BETWEEN THE δ- AND δ+ POLES OF A POLAR COVALENT MOLECULE. 2. POLAR COVALENT SUBSTANCES HAVE PERMANANT DIPOLAR MOLECULES, THE DIPOLE ATTRACTION IS NOT PERMANENT. • DIPOLE ATTRACTIONS ARE STRONGER THAN Van der Waals attractions. • THE STRENGTH OF DIPOLES INCREASES WITH IONIC CHARACTER.

  4. The DIPOLE-DIPOLE ATTRACTION (POLAR ATTRACTION): • DIPOLE-DIPOLE (POLAR or DIPOLE) ATTRACTIONS, IN COVALENT POLAR MOLECULES that INCLUDE SO2 AND H2S. AS IONIC CHARACTER INCREASES GREATER MOLECULAR polarity CAUSES GREATER BOND POLARITY CAUSES CAUSES • EFFECTS OF STRONGER ATTRACTIONS. • HIGHER BOILING TEMP. • HIGHER MELTING TEMP • INCREASING HARDNESS OF SOLID STATE. STRONGER DIPOLE ATTRACTIONS CAUSES

  5. THE HYDROGEN BOND ATTRACTION • A VERY STRONG DIPOLE ATTRACTION THAT OCCURS WHEN H IS BONDED TO F,O,N IN AN ASYMETRICAL MOLECULE. • IT IS NOT A TRUE BOND. • IS UNUSUAL IN THAT IT HAS A BOND LENGTH, CAUSES H2O TO EXPAND ON FREEZING. • BECOMES STRONGER WITH INCREASING IONIC CHARACTER OF THE MOLECULE. THE δ- OF OXYGEN ATTRACTS TO A + ION THE δ+ OF H ATTRACTS TO A – ION, IONIC CRYSTAL LATTICE H-BOND BETWEEN δ- AND δ+

  6. The white arrows represent H-bonds which: -order the molecules into a crystal formation. -cause spacing between the molecules in the solid phase – causes expansion of ice.. δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ H H H H H H H H H H H H OXYGEN OXYGEN OXYGEN OXYGEN OXYGEN OXYGEN δ- δ- δ- δ- δ- δ- H BOND ATTRACTION

  7. δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ δ+ H H H H H H H H H H H H OXYGEN OXYGEN OXYGEN OXYGEN OXYGEN OXYGEN δ- δ- δ- δ- δ- δ- MOLECULE TO ION ATTRACTION ATTRACTION MOLLECULE ION ATTRACTIONS ARE VERY STRONG AND HARD TO BREAK, MAKING THE SEPARATION OF WATER AND SALTS CONSUME LARGE AMMOUNTS OF ENERGY. THE MOLLECULE TO ION ATTRACTION BETWEEN THE δ- OF THE OXYGEN POLE OF WATER AND THE + ION. - ION THE MOLLECULE TO ION ATTRACTION BETWEEN THE δ+ OF THE HYDROGEN POLE OF WATER AND THE – ION. + ION

  8. ELECTROSTATIC (IONIC) ATTRACTION • Electrostatic ATTRACTIONS STTRACT POSITIVE IONS TO NEGATIVE IONS IN A CRYSTAL LATTICE SOLID WHERE: • THE IONS CANNOT MOVE AND THUS CANNOT CARRY A CHARGE (CONDUCT). • THE ATTRACTIONS ARE SO STRING THAT THE CRYSTAL IS HARD AND BRITTLE WITH VERY HIGH MELTING AND BOILING POINTS.\ • WHEN THE IONS DISSOLVE IN WATER, THEY CAN CARRY A CHARGE. Na+ The lines represent the electrostatic attraction. Notice the ions are in a regular, predicable geometrical arrangement. There is no randomness (LOW ENTROPY) Cl-

  9. Fracture planes of ionic crystals, brittleness.

  10. ORDERING OF MELTING AND BOILING POINTS INCREASING MELTING AND BOILING POINTS  NON-POLAR COVALENT - Order based on molar mass. POLAR COVALENT - Order based on ionic character IONIC - Order based on ionic character COVALENT NETWORK SiO2 C(s) diamond METALLIC ORDER METALS BASED ON MASS

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