Shapes of molecules

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Shapes of molecules

Key ideas

  • In any molecule, the arrangement of electrons in dot and cross diagrams are arranged in groups. A group is defined as number  bonding pairs between the central atom and one of the atoms surrounding it. The lone pairs of one atom are significant in triagonal planar and tetrahedral.
  • The number of electron groups determine the shape of the molecule.

The chemist's way of drawing in 3D

The lines represent bonds that are parallel to the plane of the paper.

The wedges represent bond that are closer to you. They are bonds that are closer than the plane of the paper.

The dashed lines represent bonds that are furthest away from you. They are bonds that are moved away from the plane of the paper.

(http://i48.tinypic.com/34sm2c3.jpg)

General rule for shapes of molecules

Areas of electron density repel each other and try to move as far away from each other as possible.

How lone pairs of electrons effect the shape

In molecules like water which has two lone pairs in it's outer shell and two bonding pairs with the hydrogen…

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