Error message

  • Deprecated function: Return type of DatabaseStatementBase::execute($args = [], $options = []) should either be compatible with PDOStatement::execute(?array $params = null): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2244 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::current() should either be compatible with Iterator::current(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::next() should either be compatible with Iterator::next(): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::key() should either be compatible with Iterator::key(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::valid() should either be compatible with Iterator::valid(): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::rewind() should either be compatible with Iterator::rewind(): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /home/dh_sj288g/stemcore.org/includes/database/database.inc).
  • Deprecated function: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in drupal_random_bytes() (line 2268 of /home/dh_sj288g/stemcore.org/includes/bootstrap.inc).
  • Deprecated function: rtrim(): Passing null to parameter #1 ($string) of type string is deprecated in url() (line 2349 of /home/dh_sj288g/stemcore.org/includes/common.inc).
  • Deprecated function: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in url_is_external() (line 2393 of /home/dh_sj288g/stemcore.org/includes/common.inc).
  • Deprecated function: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in url_is_external() (line 2395 of /home/dh_sj288g/stemcore.org/includes/common.inc).
  • Deprecated function: ltrim(): Passing null to parameter #1 ($string) of type string is deprecated in url() (line 2311 of /home/dh_sj288g/stemcore.org/includes/common.inc).

Chapter 4 Videos

  • Chapter 4 Part 1  Review of Covalent Bonding, Drawing Line Bond Structures
  • Chapter 4 Part 2  Line Bond Structures (continued)
  • Chapter 4 Part 3  Structural Formulas vs. Molecular Formula, Condensed and Skeletal Structural Formulas
  • Chapter 4 Part 4  Molecular Geometry
  • Chapter 4 Part 5   Molecular Geometry, Valence Shell Electron Pair Repulsion Theory (VSEPR)
  • Chapter 4 Part 6   Molecular Geometry of Large Molecules 
  • Chapter 4 Part 7  The Distribution of Electrons in Molecules:  Bond Polarity, Electronegativity
  • Chapter 4 Part 8  The Distribution of Electrons in Molecules:  Polarity of Molecules 
  • Chapter 4 Part 9  The Distribution of Electrons in Molecules: Formal Charge
  • Chapter 4 Part 10  Noncovalent Interactions:  Hydrogen Bonding, Dipole-Dipole Forces, London Dispersion Forces, Ion-Dipole  Interactions, Salt Bridges