Molecular geometry is the general molecular structure as determined by the atomic nuclei’s relative positions. For the general molecular formula A refer to central atom B refer to atoms attached to central atom and E refer to central atom pair.
For example AB2E2 is shown as the formula of water which has two bonded hydrogen atom B and two lone pair E.
Compounds Around A Central Atom That Five Electron Pair:
AB5 Molecular geometry :
When the central atom of a molecule is surrounded only five bondig electron pairs. The molecular element is trigonal bipyramidal. The heavier group VA element PAs Sb from some covalent compound by sharing all five of their valence.
When the central atom of a molecule is surrounded by four bonding electron pairs and by one lone pair of electron the molecular geometry is seesaws e.g SF4 TCl4 The sulphur has five electrons pairs around it four from the SF bond and one from the non bonding pairs. The five electron pairs about sulphur should have a trigonal bipyparmidal arrangement.
When the central atom of a molecule is surround by three bonding electron pair and two lone pair of electrons. It gives a T shaped geometry e.g CIF3
Has five electron pairs around the central Cl atom two of them are lone pair and the rest of the three bonding pairs. The VSEPR Theory predicts trigonal bipyramidal geometry for the presence of five electron pairs.
When the central atom of a molecule is bond to the two of another element and has three non bonding pair on it. The molecular geometry is linear e.g XeF2. The three lone pair on Xe occupy the equatorial position of the trigonal bipyramidal arrangement giving a linear geometry.
Geometry of XeF2
Molecules with six electron pair around a central atom…….
AB6 Molecular geometry:
When the central atom of a molecule is surround only by six bonding electron pairs. There is no bonding pair, then the geometry of the molecule is octahedral. Examples of type AB6 are the halide of the group viA elements in the 6 oxidation state. The Lewis structures of sulphur hexafluoride.
Molecule in which the central atom is surround by six electron pairs of which one is lone pair .The molecule adopts the shape of a square pyramid. While BrF8,IF5 and SbCI5 etc. will follow square pyramidal geometry, comprising a single pair. In IF6 the lone pair on iodine occupies one of the six equivalent positions in the octahedral arrangement giving a square pyramidal geometry.
Molecules in which the central atom is surround by six electron pair Out are lone pairs they are placed on opposite sides of the molecules resulting in a square planner shape.
Example of this types are ICI4, BrF4 etc. This result is square planer geometry.