B. Ionic bonding and Structures of Ionic Compounds Ionic Compounds Containing Polyatomic Ions Polyatomic ions work in the same way as simple ions The covalent bonds hold the polyatomic ion together so it behaves as a unit

Writing Lewis Structures for Polyatomic Ions

2- [SO4]2-

- [NO2]-

+ [NH4]+

Objectives SWBAT understand molecular structure, be able to predict molecular geometry from the number of electron pairs and to apply the VSEPR model to molecules with double bonds in a virtual laboratory.

A. Molecular Structure The atoms in a molecule have a three dimensional arrangement, Water - bent LQHS

A. Molecular Structure Linear structure – atoms in a line Carbon dioxide

A. Molecular Structure Trigonal planar – atoms in a triangle BF3

A. Molecular Structure Tetrahedral structure Methane CH4

B. The VSEPR Model Valence shell electron pair repulsion (VSEPR) model Molecular structure is determined by minimizing repulsions between electron pairs

B. The VSEPR Model Two Pairs of Electrons BeCl2 180o - linear (Note, this is an ionic compound exception AND an octet rule exception!)

B. The VSEPR Model Three Pairs of Electrons BF3 120o – trigonal planar

B. The VSEPR Model Four Pairs of Electrons CH4 109.5o – tetrahedral

B. The VSEPR Model

B. The VSEPR Model

C. Molecules with Double Bonds When using VSEPR model to predict molecular geometry of a molecule a double bond is counted the same as a single electron pair Virtual Lab LQHS