Understanding VSEPR Theory

VSEPR Theory stands for Valence Shell Electron Pair Repulsion Theory. It helps us figure out the shapes of molecules by looking at how electron pairs push away from each other around a central atom.

Here are some important points to remember:

• Electron pairs: There are two types of electron pairs.

  • Lone pairs are not bonding with other atoms.
  • Bonding pairs are connected to other atoms. Both kinds of pairs take up space and change how the molecule looks.

• Molecular shapes: Some common shapes we find are:

  • Linear: This shape has a bond angle of 180°.
  • Trigonal planar: The bond angle here is 120°.
  • Tetrahedral: This shape has a bond angle of about 109.5°.
  • Trigonal bipyramidal: The bond angles are 90° and 120°.
  • Octahedral: In this shape, all bond angles are 90°.

• How to predict shapes: We can use the formula $AX_n$ to predict how these shapes will look. In this formula, $A$ represents the central atom, and $X_n$ are the atoms that are bonded to it.

Overall, VSEPR Theory makes it easier for us to predict how molecules will shape and what their angles will be.