lewis structures, molecular geometry, polarity, intermolecular forces
DESCRIPTION
Lewis Structures, Molecular Geometry, Polarity, Intermolecular Forces. Kelly Franks, Juliet Hurvich , Lauren Cunningham. LEWIS STRUCTURES. Key Terms & Tips:. The pair of dots between two symbols represents the shared pair of a covalent bond. - PowerPoint PPT PresentationTRANSCRIPT
Lewis Structures, Molecular Geometry,
Polarity, Intermolecular Forces
Kelly Franks, Juliet Hurvich , Lauren Cunningham
➔ The pair of dots between two symbols represents the shared pair of a covalent bond.
➔ Each fluorine atom is surrounded by three pairs of electrons that are not shared in bonds.
➔ An unshared pair, also called a lone pair, is a pair of electrons that is not involved in bonding and that belongs exclusively to one atom.
➔ Covalent Bonds are represented by dashes
➔ Valence Electrons: the outer level of electrons
➔ Resonance Structure: one of two or more Lewis structures for a single molecule can be drawn to represent a molecule
➔ Bond Energies: Single bond < Double bond < Triple bond
Key Terms & Tips:
1. Draw skeletal structure of compound showing what atoms are bonded to each other. Put least electronegative element in the center.
2. Count total number of valence e-. Add 1 for each negative charge. Subtract 1 for each positive charge.
3. Complete an octet for all atoms except hydrogen4. If structure contains too many electrons, form double and triple
bonds on central atom as needed.
DRAW, COUNT, COMPLETE, FORM
Lewis Structure Steps:
VESPR Theory (Valence eletrron shell pair repulsion) -- used to predict the shape of individual molecules based upon the extent of electron-pair electrostatic repulsion
Definitions
1. Identify the name and shape of the bond angles of perchlorate.
2. Identify the name and shape of the bond angles of phosphorus fluoride.
Sample Problems:
● Polarity-- how equal bonding electrons are shared between elements
● Polar Bond or Polar Covalent Bond-- covalent bond with greater electron density around one of the two atoms
● Electronegativity-- the ability to attract electrons
Definitions:
● If the difference in electronegativities between atoms is:○ 0 to .3 = nonpolar covalent bond ○ .4 to 1.7 = polar covalent bond ○ greater than 1.7 = ionic bond
Determining Type of Bond
● usually soft and squishy● not soluble in water● can’t conduct electricity● low melting/boiling point
Properties of Covalent Bonds
● hard and brittle● tightly packed solids in a crystal lattice● usually soluble in water ● conducts electricity when dissolved● high melting points
Properties of Ionic Bonds
1) Classify NaCl as ionic, nonpolar covalent, or polar covalent.
2) Classify PCl3 as ionic, nonpolar covalent, or polar covalent.
Questions
• Intermolecular Force- attractive force between molecules
• These forces hold atoms together• If you have one type of force, you
automatically have all the forces weaker than that one
Key Terms & Tips:
1. London Dispersion Forces2. Dipole-Induced Forces3. Dipole-Dipole Forces4. Hydrogen Bonds
Forces Weakest to Strongest:
• also called Van Der Waals Forces• attractive forces between 2 nonpolar
molecules• very brief interaction
London Dispersion Forces
• also called dispersion forces• attractive forces that arise as a result of
temporary dipoles induced in atoms or molecules
Dipole-Induced Forces
• attractive forces between polar molecules• oppositely charged ends of the molecules
will attract each other
Dipole-Dipole Forces
• hydrogen of one molecule attracted to the directly connected oxygen, nitrogen, or fluorine of another
• special kind of dipole-dipole bond
Hydrogen Bonds
• attractive forces between an ion and a polar molecule
• need to be 2 different types of molecules
Ion-Dipole Forces
1. Which of these molecules is capable of forming a hydrogen bond?a. MgO b. HF c. HCl d. NaF
2. What is the strongest intermolecular force in the molecule HCl?3. What type of force is acted on CH4?
Questions:
http://quizlet.com/34556897/prybella-midyear-project-flash-cards/