Metals have a lot of important properties:
- They are shiny (or can be polished to shine)
- They conduct electricity
- They conduct heat
- They can withstand high temperatures
- They can be pounded into different shapes
Most of the periodic table is made up of metals. The majority of metals are more reactive than hydrogen and are normally found in their ionic forms (as positively charged ions involved in solid crystals or dissolved in water).
The activity series was created by alchemists who found that some metals react more easily with most metal ion solutions than other metals do.
The reactions that can occur between neutral metal atoms and metal ions are part of a special class of reactions called oxidation-reduction reactions (redox). Oxidation is the loss or one or more electrons and reduction is a gain of one or more electrons. Oxidation and reduction changes are typically called half reactions because you need both halves for a reaction to occur. To balance redox equations you need to make sure that the number of electrons lost is equal to the number of electrons gained.
The activity series is useful because you can use it to predict which equation represents a reaction that will occur. Even though hydrogen is not a gas it is included in the activity series. This is because hydrogen takes a positive nature of a metal in its role in strong acids. The main reason it is included is because these acids are simple and convenient reagents that can quickly establish where an unknown metal stands in the series. For example is a metals reacts with dilute HCl, it is above hydrogen however if a metal does not react with dilute HCl, it is below hydrogen in the series.