Conductivity The free electrons can move, and so when electrons are pushed in at one end of a piece of metal others come out at the other end. There are no empty spaces in the metal. The easiest way to visualise this is as a hose filled with marbles; when one goes in another comes out immediately at the other end. Thus current can flow through metals. It is this presence of available electrons in metals that enable them to be used to generate current in batteries.
Lustre The lustre, or shine, of metals is caused by the electrons reflecting light. All pure metals reflect well. Metals that do not seem to do so, like lead, are coated with a thin layer of oxide (rust). If this layer is scraped off, the reflective metal can be seen underneath.
Strength The pull between the layers of positive ions and negative electrons is very strong and holds the layers tightly together. This is not immediately obvious from this model of bonding.
Being Prone to Corrosion The free electrons can be absorbed by other substances, such as oxygen gas in the atmosphere. When this happens there is an imbalance of electrons and positive ions in the metal, and the unbalanced metal ions will form ionic bonds with other chemicals, and rust is produced.