Chemical Bonds

#review

Definition of a Bond

• Bonds are formed when electrons are shared or exchanged between atoms:

Types of Bonds:

Intermolecular

• Very weak chemical bond - Electrostatic interactions between molecules

Dipole

• An pair of equal and opposite charges separated by distance

Polar Molecules:

• Molecules where one end is partially positive and the other is partially negative
  • A molecule with 2 poles is a Dipole

Dipole-Dipole interaction

• Polar molecules that have electrostatic interactions through their partial positive or negative poles, orientating to maximize attraction forces and reduce repulsion forces

Hydrogen Bond

• A special dipole-dipole bond where one dipole is a H, and the other is a O, N or F

Van der Walls Force (London Dispersion Force)

• The electron cloud around atoms can temporarily sway to one side, creating a transient dipole.
  • This then induces a dipole in a neighbouring atom, creating a weak dipole-dipole.
• Found in all molecules, but are the only Intermolecular bond found in non-polar molecules.

Intramolecular

• Strong Chemical bonds holding atoms together in a molecule

Ionic bond

• A large electronegative difference: causes the electropositive atom to transfer electron(s) to an electronegative atom, creating cations and anions (opposites attract, same repel).

Covalent Bond

• Medium to low electronegative difference: causes the bonding electrons to be shared between the bonding atoms.
• The covalent bond is specifically the attracting force between the bonding electrons and the nuclei that holds the atoms together in a molecule.