Determining Molecular Polarity

Molecules

Shapes of Molecules

The shapes of molecules are the last clue for helping determine molecular polarity:

Lewis Diagrams

Lewis Diagrams and Structures are very useful for helping us predict molecular polarity.

Answers to today's examples:

NOTE: Some of the dots/crosses representing electrons are unclear. Please save the image onto your computer and enlarge it to see the details.

Introduction to Molecules

Substance Type Overview

It is very important to understand that "Matt" is not an attractive force, so please do not use it as an answer in assessments.

Chart - Type of Solid, Type of Particle, Attractive Forces Between Particles

http://chemicalminds.wikispaces.com/file/view/solidsANSWERS.pdf

This is a fully answered chart for multiple types of solids, same type of question from one of the question sheets from today.

Molecular Solids

Molecular Solids have some characteristic properties:

• low m.p./b.p.
• electrical and thermal insulators
• often brittle

These properties need to be explained in terms of the forces between the molecules (particles). These forces are called van der Waal's forces. Before we can understand these, we need to understand molecular polarity, which requires us to understand intra-molecular bonding (covalent), shapes and electron cloud size.

Covalent Networks

With Mr Nicoll away, we had to make our own summary about the structure and characteristic properties of covalent network solids. This group includes diamond, graphite and silica (glass).

Diamond

Silica: Red = Oxygen; Blue = Silicon

Metallic Solids

Most elements are metals. Metals have some characteristic properties which can be explained by the metallic bond and the structure of metals in their solid state:

1. Electrical Conductivity
2. Thermal Conductivity
3. Malleability/Ductility
4. Relatively High m.p (except Hg)

Ionic Solids

Photo of Ionic Solids Video