Archive for the ‘ Obj 2-Chem Bonds ’ Category

Obj 2-Chemical Bond & its Characteristics

Chem Bonds =divided into two (Intramolecule / Intermolecule)

  • Intramolecular bond

Polar covalent bond [Credits : Encyclopædia Britannica, Inc.]

1) Covalent

– a bond between non metal + non metal                                                                         by sharing electron to achieve stable electronic configuration

– electron shared = no of bonds

– < 1.7 difference electronegativity (less ionic)

  • Polar = when atom is more electronegative than another
  • Non-polar = when electron equally shared

2) Ionic (electrostatic forces)

– a bond between metal (low e) + non metal (high e)                                                  by electron transfer

– > 1.7 difference electronegativity (more ionic)

– cation (+ ion) / anion (- ion)

3) Metallic

– a bond between metal + metal in crystal lattice

– have low ionization energy                                                                                                (so electron move around n act as cement that hold metal ions)

– lustrous / malleable / ductile

  • Intermolecular Bond

1) Hydrogen bond

– electrostatic attraction between an electronegative atom (O / N)                             + a hydrogen atom that is covalently bonded to 2nd electronegative atom

– increase electronegativity of atom bounded to hydrogen = increase bond strength

-can be either intermolecular o intramolecular

2) Van der Waals

-short-range forces / between molecules or parts of molecules / where atoms attract when they are at certain distance / and repel when the atoms approach (tendency to maintain distance)

-more significant when (increase pressure / decrease temperature)

3)Hydrophobic Attraction / Interaction (Molecule – Ion Interaction)

-Interaction / between non-polar side chain molecule / and other non-polar side chain molecule / which tend to aggregate minimizing surface area exposed to water (to avoid water molecules) / allowing these molecules to associate with each other in aqueous environment