physci(lesson 1)

• Polarity refers to the way in which atoms bond with each other.
• The polarity of bonds mainly arises from

  the act between molecules and atoms

  with various electronegativity.
• Electronegativity is the ability of an atom

  to attract electrons to it.
• A polar molecule arises when one of the

  atoms exerts a stronger attractive force on

  the electrons in the bond it usually arises to

  the molecules with ionic bond.
• It is usually formed when the one end of the molecule is

  said to possess more number of positive charges and

  whereas the opposite end of the molecule has negative

  charges, creating an electrical pole.
• Non polar molecule arises with equal sharing of the bond

  electrons, arise when the electronegativities of the two atoms

  are equal.
• Non polar are molecules which does not have the charges

  present at the end
• Dipole means having two electrically charged regions or

  poles.
• The polarity of a bond is

  determined by a periodic

  concept called electronegativity.
• ·Electronegativity is an

  expression of an atom's

  tendency to attract electrons in a

  chemical bond.
• The attractive force that operates between

  the molecules is called intermolecular force.
• forces within molecules

  which holds atoms together in molecules are

  called bond
• 3 TYPES OF INTERMOLECULAR FORCES

  1. london dispersion force
  2. dipole -dipole
  3. hydrogen bond
• London Dispersion Force is the weakes intermolecular forces
• Dipole- dipole These forces occur when the partially positively charged part of a molecule interacts with the partially negatively charged part of the neighboring molecule
• Dipole-dipole are the strongest intermolecular force of attraCtion
• 2 Types of Dipole-Dipole Force

  1. Instantaneous Dipole
  2. Induced Dipole
• Instantaneous Dipole refers to a certain condition where the electrons concentrate or crown on one side at an instant. That side becomes positive and the other side becomes negative, although temporarily.
• The positive end of the dipole exerts an attractive force on thenearby electron, causing an adjacent atom or molecule to become another dipole called induced dipole.
• London force occurs between all atoms and molecules and in non- polar substances. This force is relatively weak but itcauses substances which are normally in gas form to liquefy at low temperatures or high pressure.
• Hydrogen bonding This is a special kind of dipole-dipole interaction that occursspecifically between a hydrogen atom bonded to either an oxygen, nitrogen, or fluorine atom.
• Hydrogen Bonding is a relatively strong force of attraction between molecules, and considerable energy is required to break hydrogen bonds