💯 The Metal Reactivity Explained with Fair Examples

📢 Receive Comprehensive Mathematics Practice Papers Weekly for FREE 😊
Click this link to get: ▶️▶️▶️ https://iitutor.com/email-list/ ◀️◀️◀️

By observing how readily different metals react with oxygen, water and dilute acids it is possible to determine an order of reactivity and thus rank these metals in an activity series. Some common metals are arranged according to their ability to displace hydrogen from dilute acids and water. The metals are arranged from the most reactive or most easily oxidised, potassium, to the least reactive or least easily oxidised, gold.
• The most reactive metals are found in Group I (K, Na) and Group II (Ca, Mg)
• In general, the metal reactivity increases as moves to the left-hand side of the Periodic Table and the metal reactivity increases as moves down within the same group in the Periodic Table
• Group III metals are less reactive than Groups I and II, although some transition metals (e.g Fe, Zn) have similar reactivity to Group III.
• The soft metals at the bottom of Group IV are less reactive than Group III metals.
• The least reactive metals are found in the lower periods of the transition metals (Ag, Au) or in the soft, heavy metal region (Pb).
The reactivity of the other metals is difficult to relate to their periodic positions without using other information.
The use of a particular metal is determined not only by its physical properties but also by its reactivity. Gold, silver and platinum are quite unreactive and undergo little or no corrosion. Because these metals do not readily tarnish they retain their shiny lustre and make attractive jewellery.
• Magnesium
This very reactive metal reacts readily with oxygen to produce a bright, white light. This chemical property can be used in flashbulbs and fireworks to provide illumination and visual displays. Magnesium is attached to underground steel petrol tanks to protect them from corrosion. The magnesium corrodes in preference to the steel.
• Aluminium
In the basic steel-making process, excess carbon is oxidised using a blast of pure oxygen. A reactive metal such as aluminium is added to react with the oxygen to ensure excess oxygen does not remain in the molten steel. The aluminium oxide formed floats to the surface for removal. House gutters are now commonly made from aluminium as it is not subject to corrosion due to the rapid reaction of aluminium with oxygen to form a surface passivating layer.
• Zinc
Like magnesium, zinc is reactive enough to be used as sacrificial anodes to protect steel structures. Lumps of zinc are attached to the hulls of ships or as collars to propellers. The zinc oxidises preferentially and protects the steel. Zinc's reactivity is also used to protect iron and steel. Galvanising steel cans will protect the can from corrosion as long as some zinc is present.
• Copper
Copper's low reactivity with oxygen and water makes it more suitable than iron for water pipes. Although copper is more expensive than iron, it is now preferred for plumbing.  
• Gold
Gold is the least reactive of all metals. This has been known since ancient times and throughout history has been used to make jewellery and fine ornaments. Because it is an excellent conductor of electricity and does not tarnish, it is also widely used in electrical connections in computer and electronic circuits. Gold also has several applications in the space industry as it is an excellent reflector of infra-red radiation and is chemically inert. For example, the umbilical cord joining the astronaut Edwin White to his spacecraft during the historic ‘walk’ in space was plated with gold to reflect thermal radiation. Gold was also used on the undercarriage of the Apollo 11 lunar module which first placed humans on the moon.
• Calcium
Owing to its high reactivity, the uses of calcium are restricted to situations where its reactivity can be used to advantage. Calcium is added to some steels to remove any remaining traces of oxygen, sulphur and phosphorus. It is also used in electronic vacuum tubes because it combines with any traces of oxygen that remain thus producing a better vacuum.
• Titanium
Titanium is used in holding tanks and pipes in desalination plants, which convert seas water into freshwater, and factories produce or use acids. The ability of titanium to resist corrosion makes it an ideal metal in these corrosive environments.